abstract book - iitr.ac.in · bhas bapat, sumit srivastav and deepak sharma it-01 5. analytical...

8th Topical conference (TC-2020)

on Atomic and Molecular

Collisions for Plasma Applications

ABSTRACT BOOK

Organized By

Department of Physics,

Indian Institute of Technology Roorkee,

Roorkee-247667, Uttarakhand, INDIA

SPONSORS

8th Topical conference (TC-2020) on Atomic and Molecular Collisions for Plasma Applications

Advisory Committee A. K. Chaturvedi (IIT Roorkee)

A. K. Das (DST New Delhi)

Bhas Bapat (IISER Pune)

B. N. Jagatap (IIT Bombay)

B. N. Rajasekhar (AMPD BARC)

C. P. Safvan (IUAC New Delhi)

G. Ravindra Kumar (TIFR Mumbai)

Hema Ramachandran (RRI Bangalore)

K. L. Yadav (IIT Roorkee)

Lokesh Tribedi (TIFR Mumbai)

Manmohan (University of Delhi)

N. Sathyamurthy (IISER Mohali)

P. C. Deshmukh (IIT Tirupati)

R. Shankar (BHU Varanasi)

Shashank Chaturvedi (IPR Gandhinagar)

Tauheed Ahmad (AMU Aligarh)

Conveners Lalita Sharma, Assistant Professor

Rajesh Srivastava, Professor

Department of Physics, IIT Roorkee


About the Conference The 8th Topical Conference of the Indian Society of Atomic and Molecular

Physics(ISAMP) is the latest in the series of the 3-day biennial national

conferences. The present meeting will be held at the Indian Institute of

Technology (IIT) Roorkee, Roorkee from 3rd to 5th March, 2020. The theme of

the conference is ‘Atomic and Molecular Collisions for Plasma Applications'.


PLENARY TALKS

1. Plasma chemistry for modelling plasmas under extreme conditions

Shashank Chaturvedi

PL-01

2. Physics of plasmas confined by a dipole magnet

Sudeep Bhattacharjee

PL-02

3. Some of the applications of laser induced plasma of solid and solid liquid

interface

Alika Khare

PL-03

INVITED TALKS

4. First results from the IISER Pune EBIS

Bhas Bapat, Sumit Srivastav and Deepak Sharma

IT-01

5. Analytical response relativistic atomic many-body method

B. K. Sahoo

IT-02

6. Modelling of atomic polarizability for dispersion interactions

Bindiya Arora

IT-03

7. Fock-space relativistic coupled-cluster calculation of two-valence atoms

and ions

Brajesh Kumar Mani and Dilip Angom

IT-04

8. Electronically excited states of molecules: experimental and theoretical

perspectives

Aparna Shastri

IT-05

9. Dissociative electron attachment to isolated molecules and clusters

Dhananjay Nandi

IT-06

10. Diagnosis of Tokamak plasma using passive spectroscopy

Joydeep Ghosh

IT-07

11. Photoionization studies of argon inside charged fullerene

Afsal Thuppilakkadan, Jobin Jose and Hari R. Varma

IT-08

12. Shannon’s entropy in endohedrally confined atoms: Indicator of avoided

crossing and correlation energy

Jobin Jose

IT-09

13. Laser cooling and trapping of Rb at narrow blue transition

Dangka Shylla, Elijah Ogaro Nyakang'o, Rajnandan Choudhury Das and

Kanhaiya Pandey

IT-10

14. Precision quantum measurements using optical clock

Subhadeep De

IT-11

15. Spectroscopic constants and thermochemistry of some ozone depleting

systems

T. K. Ghosh

IT-12

16. Electron impact low energy studies for Di-triatomic targets

M. Vinodkumar

IT-13

17. Application of plasma produced nanostructures in surface wettability and

sensing

M. Ranjan, V. Pachichigar, Sooraj KP and S. Augustine

IT-14


18. Study of nonlinear waves in multicomponent space plasmas

N. S. Saini

IT-15

19. Strong field ionization with ultrashort orbital angular momentum beams

R. Gopal, A. Sen, A. Sinha and V. Sharma

IT-16

20. Diagnostic of Non-Thermal Atmospheric Pressure Plasma Jet Through

Emission and Absorption Spectroscopy

R. K. Gangwar, P S Srikar and S M Bakshi

IT-17

21. Multidiagnostic characterization of ultrashort and short pulse laser

produced plasmas

Pranitha Sankar and Reji Philip

IT-18

22. Neutrino-plasma interactions in gravitating degenerate astrophysical

plasmas

R. P. Prajapati

IT-19

23. Gas-phase formation of ammonia in the diffuse interstellar medium

calculation of the rate coefficients of the key steps

Sunil Kumar S, Salvi M and Raghunath O. Ramabhadran

IT-20

24. Atom-optic kicked rotor: From quantum chaos to atom interferometry

Umakant Rapol

IT-21

25. Photodissociation and dissociative electron attachment: similarities and

differences

V. S. Prabhudesai

IT-22

26. Foam structure of dopants in helium nanodroplets? Some evidences in

photoionization of acetylene doped helium droplets

Suddhasattwa Mandal, Ram Gopal, M. Shcherbinin, Robert Richter, H.

Srinivas, Marcello Coreno, Alessandra Ciavardini, A D’Elia, B Bapat, M

Mudrich, S. R. Krishnan and V. Sharma

IT-23

27. Accurate calculation of weak intermolecular interaction energy

Narendra Nath Dutta

IT-24

28. Electron induced ionization cross sections of atoms, ions and molecules

relevant to plasma applications

Ghanshyam Purohit and Daiji Kato

IT-25

POSTERS

29. Gravitational instability of partially-ionized plasma with hall current FLR

corrections flowing through porous medium

Sachin Kaothekar and R. K. Chhajlani

PP-01

30. Ionization cross sections of water molecules impacted by dressed ions

D. Jana, A. Mondal and M. Purkait

PP-02

31. Atomic-size Fraunhofer-type diffraction for electron capture in ion-atom

collision

S. Samaddar, K. Purkait and M. Purkait

PP-03

32. VUV spectroscopy of ethyl methyl carbonate

A. K. Das, S. Krishnakumar and B. N. Rajasekhar

PP-04

33. Electron impact excitation of singly charged In and Sn ions

Swati Bharti, Lalita Sharma and Rajesh Srivastava

PP-05


34. Structural, vibrational and electronic spectroscopic study of 7-(4-

trifluoromethyl) coumarin acrylamide using experimental and theoretical

methods

D. Vijay, Asim Kumar Das, B.N.Rajasekhar and A.Veeraiah

PP-06

35. Behavior of impurities in radiative improved mode plasmas of ADITYA-U

Tokamak

M. B. Chowdhuri, J. Ghosh, R. Manchanda, R. L. Tanna, K. A. Jadeja, N.

Yadava, N. Ramaiya, S. Patel, G. Shukla , K. Shah, K. M. Patel, Tanmay

Makwan , U. C. Nagora, S. K. Pathak, J. V. Raval, M. K. Gupta, M. V.

Gopalakrishna, K. Tahiliani, Rohit Kumar, Suman Aich, B. V. Nair, C. N.

Gupta and ADITYA-U Team

PP-07

36. Radial profile of visible continuum emission from ADITYA-U tokamak

plasmas

R. Manchanda, M. B. Chowdhuri, J, Ghosh, N. Yadava, N. Ramaiya, S. Patel,

U. C. Nagora, S. K. Pathak, J. V. Raval, M. K. Gupta, K. A. Jadeja, R. L. Tanna,

C. N. Gupta and ADITYA-U Team

PP-08

37. Calculations of total electron impact ionisation cross sections for

Fluoroketone and Fluoronitrile

Nirav Thakkar, Mohit Swadia, Minaxi Vinodukmar and Chetan Limbachiya

PP-09

38. Ab initio study of structure, spectroscopic constants and thermal properties

of an ozone depleting reaction

Gargi Nandi and T. K Ghosh

PP-10

39. Dissociation dynamics of multiply charged CO2 under impact of slow and

highly charged ions

S. Srivastav, D. Sharma and B. Bapat

PP-11

40. Electron Beam Ion Trap/Source for ion–molecule collisions in the non-

perturbative regime

B. Bapat, D. Sharma and S. Srivastav

PP-12

41. Orientation effect in multiple ionisation of OCS under proton and C2+

impact at 50 keV

D. Sharma, B. Bapat, P. Bhatt and C. P. Safvan

PP-13

42. Electron interaction with Para-Benzoquinone(C6H4O2) and

Naphthoquinone(C10H6O2)

Dhaval Chauhan and Chetan Limbachiya

PP-14

43. Electron impact elastic scattering cross section from acetylene

Dibyendu Mahato, Lalita Sharma and Rajesh Srivastava

PP-15

44. Electron impact excitation cross section of magnesium for plasma

application

S S Baghel, S Gupta, R K Gangwar and R Srivastava

PP-16

45. Study of the nature of impurity transport coefficients using separate atomic

databases in the ADITYA tokamak

A. Bhattacharya, J. Ghosh, M. B. Chowdhuri, P. Munshi and the ADITYA team

PP-17


46. C-R model for Ar-CO2 mixture plasma using reliable fine structure cross

sections

Neelam Shukla, Reetesh Gangwar and Rajesh Srivastava

PP-18

47. Modeling the tunneling reaction NH2+ + H2 → NH3

+ + H at interstellar

temperature by variational transition state theory

M. Salvi, Raghunath O. Ramabhadran and S. Sunil Kumar

PP-19

48. Electron Scattering from HCNO

Paresh Modak, Nafees Uddin and Bobby Antony

PP-20

49. Pulse width effect on the ionization and dissociation of Methyl Iodide in the

intense femtosecond laser field

Arnab Sen, Bhas Bapat, Ram Gopal and Vandana Sharma

PP-21

50. Double slit projectile wave interference at slow and intermediate electron

transfer collisions

Md A. K. Azad Siddiki, Nrisimhamurty Madugula, M.A. Rehman, M.R. Chowdhury,

L.C. Tribedi and Deepankar Misra

PP-22

51. Mercury hydroxide as a promising triatomic molecule to probe P, T-odd

interactions

R. Mitra, V. S. Prasannaa and B. K. Sahoo, X. Tong, M. Abe and B. P. Das

PP-23

52. Electron interaction with Fluorocompounds for application in plasma

sciences

Smruti Parikh and Chetan Limbachiya

PP-24

53. A comparative analysis of non-relativistic and relativistic calculations of

electric dipole moments and polarizabilities of heteronuclear alkali dimers

R. Mitra, V. S. Prasannaa and B. K. Sahoo

PP-25

54. Characterizing Laguerre-Gaussian pulses using angle-resolved attosecond

streaking

Irfana N. Ansari, Deependra S. Jadoun and Gopal Dixit

PP-26

55. Theoretical investigation of various inelastic processes of e-CO2 scattering

S. Vadhel, M. Vinodkumar and P. C. Vinodkumar

PP-27

56. Relativistic coupled-cluster calculations of electric dipole polarizability of

Al and In

Ravi Kumar and B. K. Mani

PP-28

57. Ion-pair dissociation dynamics in electron collision with carbon dioxide

probed by velocity slice imaging

Narayan Kundu, Anirban Paul and Dhananjay Nandi

PP-29

58. Differential cross section for positron-biomolecules interaction

Nidhi Sinha and Bobby Antony

PP-30

59. Quantum coherence in dissociative electron attachment: isotope effect

S. Swain, E. Krishnakumar and V. S. Prabhudesai

PP-31

60. Angular distribution of H - from dissociative electron attachment to H 2 at

10eV

S. Swain, E. Krishnakumar and V. S. Prabhudesai

PP-32


61. Electron ionization cross sections of C2H4 molecule

Pawan Kumar Sharma and Rajeev Kumar

PP-33

62. Laser cooling and trapping of neutral 87Rb atoms

Raj Kumar, Neeraj Singh, Anju Pal, Navpreet Kaur and Ajay Wasan

PP-34

63. Angle dependence of WES photoionization time delay from atoms trapped

in a negatively charged cage

S. Banerjee and P. C. Deshmukh

PP-35

64. Theoretical investigation on electron impact with halogen diatomic

molecule X2 (X = F, Cl, Br, I)

Hitesh Yadav, Minaxi Vinodkumar, Chetan Limbachiya and P. C. Vinodkumar

PP-36

65. Dissociative electron attachment dynamics to nitrogen dioxide

Anirban Paul, Dipayan Biswas and Dhananjay Nandi

PP-37

66. Initial results from the 22-pole ion trap experimental set-up

Roby Chacko, N. R. Behera, S. Dutta and G. Aravind

PP-38

67. Study of reaction kinetics of O + XO → X + O2

S. Naskar and T. K. Ghosh

PP-39

68. Spectroscopic properties of divalent lead halides

S. Ghosh and T. K. Ghosh

PP-40

69. Camphor doped helium nano-droplets in soft X-Ray radiation

S. Sen, S. Mandal, R. Gopal, R. Richter, M. Mudrich, V. Sharma and S.

Krishnan

PP-41

70. Significance of dynamic quadrupole polarizabilities on the determination

of magic wavelengths of the clock transitions in the alkaline-earth metal

ions

Mandeep Kaur, Sumeet, B K Sahoo and Bindiya Arora

PP-42

71. Electron impact ionization cross section of atoms and molecules using

binary-encounter-Bethe model

Piyush Sinha and Shivani Gupta

PP-43

72. Photoelectron velocity map imaging spectroscopy facility for probing

astrophysical anions

Saroj Barik and G. Aravind

PP-44

73. Probing molecular chirality by laser-driven electronic fluxes

Sucharita Giri and Alexandra Maxi Dudzinski

PP-45

74. Penning spectroscopy of ionic molecular cluster in he nanodroplets

Suddhasattwa Mandal, Ram Gopal, Robert Richter, Marcello Coreno,

Alessandra Ciavardini, Alessandro D’Elia, Bhas Bapat, Marcel Mudrich,

Vandana Sharma and Sivarama Krishnan

PP-46

75. Electron interactions with plasma processing gases

Rakesh Bhavsar, Yogesh Thakar and Chetan Limbachiya

PP-47

76. Design of Penning trap setup for lifetime studies of metastable states in

atomic ions.

Deepak Chhimwal, S. Kumar, L. Nair, W. Quint, C.P. Safvan and M. Vogel

PP-48


77. Electron and positron impact ionization cross sections of nitrogen

molecules

Kamlesh Kumar Jat and Ghanshyam Purohit

PP-49

78. Electron induced processes on plasma relevant materials, Be and W atoms

Kailash Chandra Dhakar and Ghanshyam Purohit

PP-50

79. Exploring quasi molecular phenomenon using heavy ion heavy atom

collisions

R. Gupta, C. V. Ahmad, K. Chakraborty, D. Swami, G. Sharma and P. Verma

PP-51

80. Detailed collisional radiative model for laser produced Zn plasma

Shivam Gupta, Reetesh Kumar Gangear and Rajesh Srivastava

PP-52

81. Saturated absorption spectroscopy of molecular iodine for frequency

stabilization of 739 nm laser

Lakhi Sharma, A. Roy, S. Panja and S. De

PP-53

82. Strong field ionization from atoms and nano-tips in structured beams

Abhisek Sinha, Debobrata Rajak, Sanket Sen, Ram Gopal and Vandana Sharma

PP-54

83. Iron impurity behavior in the ADITYA tokamak

S. Patel, A.K. Srivastava, M. B. Chowdhuri, R. Manchanda, A. Bhattacharya,

J. V. Raval, U. Nagora, P. K. Atrey, R. L. Tanna, J. Ghosh and ADITYA Team

PP-55

84. Partial wave analysis of electron scattering from argon atoms

David Joseph and Naveen Chahal

PP-56

85. High harmonic generation in bichromatic inhomogeneous pulses

Ankur Mandal and Pranawa C. Deshmukh

PP-57

86. Electron-impact cross sections of isovalent AlCl & AlF molecules from

0.1~eV to 5~keV

S. Kaur, A. Bharadvaja and K. L. Baluja

PP-58

87. Positron impact ionization cross sections from pentane isomers

Vardaan Sahgal, A. Bharadvaja, S. Kaur and K. L. Baluja

PP-59

88. New ultrafast laser and instrumentation facility at PRL Ahmedabad for

femtosecond and attosecond science

R. K. Kushawaha, Madhusudhan P, Rituparna Das, Pranav Bhardwaj,

Swetapuspa Soumyashree, Pooja Chandravanshi and Nimma Vinitha

PP-60

89. Edge temperature and density measurements in ADITYA-U Tokamak with

helium spectral line intensity ratio

Tanmay Macwan, Sharvil Patel, Nandini Yadava, Ritu Dey, Kaushlender Singh,

Suman Dolui, Rohit Kumar, Suman Aich, Malay B Choudhary, Ranjana

Manchanda, R. L. Tanna, K. A. Jadeja and K. M. Patel and J. Ghosh

PP-61

90. Neutral and impurity influx measurement from limiter and wall of Aditya-

U Tokamak

Nandini Yadava, J. Ghosh, M. B. Chowdhuri, R. Manchanda, Sripathi

Punchithaya K, Ismyil, N. Ramaiya, Ritu Dey, Tanmay Macwan, S. Patel, R. L.

Tanna and Aditya-U team

PP-62


91. Diffraction of proton beams by an optical crystal: Kapitza-Dirac effect for

plasma ions with spin

Sushanta Barman and Sudeep Bhattacharjee

PP-63

92. Electron impact excitation of highly charged iso-electronic series of Ge like

Ba, Te, Sn, Cd ions

P. Malker and L. Sharma

PP-64

93. Dynamics of dissociative electron attachment to ethanol

S. Das, S. Swain and V. S. Prabhudesai

PP-65

94. Effect of background static gas on momentum images in velocity slice

imaging of dissociative electron attachment

S. Das, S. Swain and V. S. Prabhudesai

PP-66

95. Theoretical investigation of the electronic structure of HgH+

R. Bala, H. S. Nataraj, M. Kajita and M. Abe

PP-67

96. Analysis of the visible transitions in tungsten (WIX and WX) observed with

electron beam ion trap

Priti, Daiji Kato, Izumi Murakami, Hiroyuki A. Sakaue and Nobuyuki

Nakamura

PP-68

97. Plasma screening effect on excitation energies and transition data of P-like

Zn

Arun Goyal, Sunny Aggarwal, Narendra Singh and Man Mohan

PP-69

98. Strongly coupled plasma effect on excitation energies and transition data of

Ca VI

Sunny Aggarwal, Arun Goyal and Man Mohan

PP-70


PL-01

Plasma chemistry for modelling plasmas under extreme conditions

Shashank Chaturvedi

Institute for Plasma Research, Gandhinagar

Plasmas cover an enormous range in terms of density and temperature. The elemental

composition can also vary depending upon the material from which plasma is produced. As a

result, there can be large variation in the population distribution of different atomic, molecular

and ionic species, not to mention excited states. This implies a correspondingly large variation

in physical & chemical properties, which is why plasmas find a variety of uses ranging from

Nuclear Fusion at one extreme to applications in industrial tools, medical/health sector, textile

sector, waste disposal, aerospace and so on. The computational modelling of each of these

systems must take into account not just the physics but also the chemistry involving all possible

species. In this talk, we will use two examples to highlight the computational complexities

involved in modelling plasmas. The first is industrial plasma systems, and the second is warm

or hot dense plasmas produced under shock-loading conditions.


PL-02

Physics of plasmas confined by a dipole magnet

Sudeep Bhattacharjee*

Department of Physics, Indian Institute of Technology Kanpur - 208016

*[email protected]

Brief overview: The talk will cover the properties of a plasma confined by a dipole magnetic

field. Unlike other confinement schemes, here the plasma is confined by a unique balance

between the plasma pressure and the magnetic pressure, and resembles that of the

magnetospheric plasma surrounding our earth. We have developed such an experiment in our

laboratory. The talk will discuss about processes such as diffusion, recombination and

ionization in the plasma and their scaling with the magnetic field, including resulting density

and temperature profiles. Additionally, the talk will try to cover the setting up of the steady

state density profiles as a result of diffusion induced transport. Please find references of two

recent articles on this topic below.

References [1] Anuj Ram Baitha, Ashwani Kumar, and Sudeep Bhattacharjee, Review of Scientific Instruments 89, 023503

(2018)

[2] Anuj Ram Baitha, Ayesha Nanda, Sargam Hunjan and Sudeep Bhattacharjee Plasma Res. Express 1, 045005

(2019)


PL-03

Some of the applications of laser induced plasma of

solid and solid liquid interface

Alika Khare

Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, India

E-mail: [email protected]

Laser induced plasma (LIP) is finding its application in a very broad perspective. It is being

used extensively in material processing with a high degree of precision. It has qualified as a

source of coherent X –Rays and higher harmonics generation as well as a source of highly

energetic electrons/ions and neutral beams. Whenever a high power laser is focused on a

medium, it results into the formation of its high density high temperature transient plasma.

When the laser is focused on the solid target, the material from the targets with in the focal

region is ablated out along with the formation of the plasma. The plasma emits its

characteristics emission which forms the basis of Laser induced breakdown spectroscopy

(LIBS), an upcoming powerful tool to identify the chemical composition of any system in any

format. LIP of solid comes out with solid density and expands in the surrounding medium. In

case surrounding medium is vacuum or a low pressure gas, then expansion is very huge and if

a substrate is placed in front of this, the constitute ions and atoms can be deposited on it

rendering the formation of thin film. This technique of deposition is termed as pulsed laser

deposition (PLD). Pulsed Laser Deposition (PLD) technique has been observed to be very

successful for the synthesis of variety of thin films with very high precision in a simple and

single step manner which could be complicated via other techniques. In the recent years, pulsed

laser ablation in liquid (PLAL) has paved a new way of synthesizing the nano particles (NP)

of any material. This technique is also single step, simple, devoid of any hazardous chemicals,

free from contamination and very versatile. The characteristics of NP can be easily tuned by

controlling the laser parameters and the surrounding liquid. The confinement of laser produced

plasma by the surrounding liquid causes highly transient extreme pressure and temperature

which prefers the growth of metastable phases which are normally not possible via other

routine chemical roots. In the present talk, some of the above applications of Laser induced

plasma shall be highlighted.


IT-01

First results from the IISER Pune EBIS

Bhas Bapat *, Sumit Srivastav and Deepak Sharma

Indian Institute of Science Education and Research, Homi Bhabha Road, Pune 411008

*[email protected]

Collisions between ions and molecules is a process that has been studied for long. Typically,

small projectile charge q and high velocities v are considered to fall in the domain of

perturbative collisions (i.e. when q/v < 1), while for high projectile charge and low velocities

the collisions are considered to fall in non-perturbative domain. In the latter case one may

approach a regime where the projectile velocity matches the average speeds of electrons in

different shells and interesting ionization patterns may emerge. In particular, charge exchange

may dominate over direct ionization, and specific ionization states may be enhanced.

In order to perform experiments in the latter category, it is necessary to generate ions in

different highly charge states with an ability to tune their energies. An electron beam ion

source/trap employing a combination of static magnetic and electric fields is a suitable source

for such studies. It is able to generate slow and highly charged ions with very narrow spread

of energies and offers high selectivity of charge state by minor tuning of parameters. Such an

ion source has recently been installed at IISER Pune. It is manufactured by DREEBIT GmbH,

Germany, and is capable of providing charge states of Argon in the range 1–16+ and virtually

any other element in a comparable range of charge states, so long as the element is available

as gaseous or liquid compound. The energy of the ions can be varied over 5–30 keV/q.

The ion source is fully operational, and coupled to an ion momentum spectrometer for

performing molecular fragmentation studies. A post-collision projectile analyser is being

added. The ion source facility will be made open to external users by the end of the year.

Preliminary results on multiple ionization of CO2 will be presented in the talk.

mailto:*[email protected]


IT-02

Analytical response relativistic atomic many-body method

B. K. Sahoo

Atomic, Molecular and Optical Physics Division, Physical Research Laboratory, Navrangpura,

Ahmedabad 380009, India

Email: [email protected]

To yield accurate results for atomic properties, it is imperative to employ potential atomic

many-body methods that account for both electron correlation and relativistic effects

rigorously. The coupled-cluster (CC) theory is considered as the gold standard for treating

electron-correlation effects [1], so relativistic version CC (RCC) method can serve for the

above purpose. However, the currently used RCC methods for atomic calculations have many

drawbacks as they can generate uncontrolled theoretical uncertainties. For example, the

commonly used expectation-value-evaluation (EVE) approach in the RCC theory involves

non-terminating series and does not satisfies the Hellmann-Feynman theorem, whereas the

finite-field (FF) approach in the RCC theory depends on the choice of a perturbation parameter.

To overcome these problems, we have implemented recently an analytic-response approach

within the RCC (AR-RCC) theory framework. In my talk, I shall discuss about the general

features of the AR-RCC theory and demonstrate its first applications to the precise

determination of local Lorentz invariance violating parameters [2] and isotope shift constants

[3].

Reference [1] I. Shavitt, R. J. Bartlett, Many-body Methods in Chemistry and Physics, Cambridge University Press,

Cambridge, UK (2009).

[3] B. K. Sahoo, Phys. Rev. A (Rapid Communication) 99, 050501 (2019).

[2] B. K. Sahoo et al, New J. Phys. (Fast Track Communication) 22, 012001 (2020).


IT-03

Modelling of atomic polarizability for dispersion interactions

Bindiya Arora

Department of Physics, Guru Nanak Dev University, Amritsar, Punjab


The dispersion interactions are fundamental for studying the structure, stability and various

properties of atomic and molecular systems. Assessing these interactions accurately can result

in new pathways towards engineering, technology and research. In this presentation I will talk

about the role of atomic polarizability for accurate evaluation of dispersion interaction. The

dispersion C6 coefficients for interatomic interactions and C3 coefficients for the interaction

of various atomic systems with different wall surfaces such as a perfect conductor, metal,

semiconductor, dielectric surfaces and carbon nano structures will be discussed. The

significance of the interactions between atoms and atomically thin films of the multi-layered

transition metal molybdenum disulfide (MoS2) dichalcogenides for their applications in

optoelectronics, sensors and storage devices will be highlighted.


IT-04

Fock-space relativistic coupled-cluster calculation of

two-valence atoms and ions

Brajesh Kumar Mani1,* and Dilip Angom2

1Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi 110016,

India 2Physical Research Laboratory, Ahmedabad - 380009, Gujarat, India

*[email protected]

Relativistic coupled-cluster is one of the most reliable many-body methods to accurately

calculate the many-electron wave functions and properties of atoms and ions [1, 2, 3]. Despite

its great potential to predict atomic properties within the accuracy commensurate with atomic

experiments or even better, its application is mostly limited to the closed-shell and one-valence

atomic systems. One of the reasons for this could be attributed to the complications associated

with its implementation for multireference systems. We have developed an all particle Fock-

space relativistic coupled-cluster (FSRCC) based method for the properties calculation of two-

valence atoms and ions [4, 5]. Using this method, we have calculated the atomic properties

which are relevant to optical atomic clock in the case of Al+ ion [5]. In this talk, I shall discuss

about the FSRCC method we have developed and also share some results in the context of Al+

atomic clock.

References [1] H. S. Nataraj, B. K. Sahoo, B. P. Das, and D. Mukherjee, Phys. Rev. Lett. 101, 033002 (2008).

[2] R. Pal, M. S. Safronova, W. R. Johnson, A. Derevianko, and S. G. Porsev, Phys. Rev. A 75, 042515

(2007).

[3] B. K. Mani, Siddhartha Chattopadhyay, D. Angom, Comp. Phys. Commu. 213, 136 (2017).

[4] B. K. Mani and D. Angom, Phys. Rev. A 83, 012501 (2011).

[5] Ravi Kumar, S. Chattopadhyay, B. K. Mani and D. Angom, (To be published)


IT-05

Electronically excited states of molecules: experimental and theoretical

perspectives

Aparna Shastri*

Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085

*[email protected]

Electronically excited states of molecules play an important role in chemical reactions

occurring in the earth’s atmosphere, laboratory plasmas, astrophysical objects, etc. A thorough

understanding of the electronic structure and spectrum of a molecule is a prerequisite to

unravelling its behaviour in complex reactions induced by highly energetic photons/other

particles. A direct method to obtain information about electronically excited states of a

molecule is through its photoabsorption spectrum and since excited states typically lie in the

ultraviolet-vacuum ultraviolet (UV-VUV) region, synchrotron radiation (SR) is an ideal source

for such studies.

Our group has an ongoing program for VUV spectroscopy of molecules using SR at the 450

MeV storage ring Indus-1, RRCAT, Indore. Over the past few years, using the two indigenously

developed beamlines (Photophysics and HRVUV) at Indus-1[1-3], high quality VUV spectral

data has been generated for several molecules, which have been included in reputed

international molecular databases [4,5].

On the theoretical side, analysis and interpretation of molecular electronic spectra is quite

challenging because of the number of degrees of freedom involved and various interactions

between them. Generally, satisfactory explanation of the observed spectral features require

extensive quantum chemical calculations which are used to predict properties like excited state

energies, their valence/Rydberg/intermediate nature, geometry changes and vibrational modes

in excited states, behaviour of excited state potential energy curves, etc. In this talk, I shall

present an overview of both experimental and theoretical aspects of the VUV spectroscopic

studies being pursued in our group. A few recent studies [6-8] will be highlighted.

References [1] A. Kalinin, D. A. Banerji, P. R. Hannurkar, M. G. Karmarkar, S. Kotaiah, S. P. Mhaskar, P. K. Nema, S. S.

Prabhu, M. P. Kumar, S. Ramamurthi, Curr Sci 82, 283 (2002).

[2] N. C. Das, B. N. Rajasekhar, S. Padmanabhan, A. Shastri, S. N. Jha, S. S. Bhattacharya, S. Bhat, A. K. Sinha,

V. C. Saini, J Opt 32, 169 (2003).

[3] Param Jeet Singh, A. Shastri, R. Sampath Kumar, S.N. Jha, S.V.N.B. Rao, R. D’Souza and B.N. Jagatap,

Nucl. Instrum Methods Phys Res A 634, 113 (2011).

[4] UV/Vis+ Photochemistry database (https://science-softcon.de/spectra)

[5]The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest

(http://satellite.mpic.de/spectral_atlas/index.html)

[6] A. Shastri, Param Jeet Singh, K. Sunanda, Asim Kumar Das and B.N. Raja Sekhar, Phys Chem Chem Phys

19, 6454 (2017).

[7] A. Shastri, Asim Kumar Das, K. Sunanda, Param Jeet Singh and B.N. Raja Sekhar, J Chem Phys 147, 224305

(2017).

[8] A. Shastri, A.K. Das and B.N. Raja Sekhar, J Quant Spectrosc Radiat Transfer 242, 106782 (2019).


IT-06

Dissociative electron attachment to isolated molecules and clusters

Dhananjay Nandi*

Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India

*[email protected]

Low energy electron-molecule collision dynamics is of great interest from fundamental as well

as practical applications. We probe dissociative electron attachment (DEA) to isolated

molecules and clusters of fundamental interest using well established techniques. Our recent

development toward the production of cold molecular target using pulsed supersonic jet

enables us to study DEA to cold molecules and clusters. The results show many exciting

observations.

In this conference, we will discuss kinematically complete measurements of DEA to

sulfur dioxide (SO2) and ammonia (NH3) using velocity slice imaging technique. Finally, we

will present our observations on DEA to small cluster of oxygen.

References [1] I. Jana and D. Nandi, Phys. Rev. A 97, 042706 (2018).

[2] I. Jana and D. Nandi, J. Phys. B: At. Mol. Opt. Phys. 52, 185202 (2019).

[3] D. Chakraborty, A. Giri and D. Nandi, Phys. Chem. Chem. Phys. 21, 21908 (2019).

[4] I. Jana V. Ramaprasad and D. Nandi, arXiv:submit/2576569 [physics.atm-clus] 14th February, 2019.



IT-07

Diagnosis of Tokamak plasma using passive spectroscopy

Joydeep Ghosh*

Institute for Plasma Research, Bhat, Gandhinagar-382428, India


Radiation emanated from a magnetically confined tokamak plasma contains enormous

information about the plasma properties. Hence, spectroscopic diagnostics remains an

important tool to diagnose the tokamak plasma. Radiation from a tokamak plasma, especially

from X-ray to NIR region are recorded either in totality or in spectrally resolved regions to

obtain various plasma parameters along with their temporal evolutions. These include size and

shape of the plasma, electron temperature, Te, ion temperature, Ti, radiation power loss, Prad,

plasma rotation velocity, recycling from the walls, impurity behavior, electric and magnetic

fields inside the plasma etc. Broadly, the tokamak plasma is divided into two areas for the

spectroscopic studies. In the edge plasma, i.e., near the boundary of the plasma column, most

of the emission is in visible region, whereas the center of plasma column mainly radiates in

VUV and X-ray wavelength regions as the plasma temperature increases manifold towards the

center of the plasma column. Adequate modelling is required to obtain plasma parameters from

the measurements. In this presentation, an overview of studies on impurity temperature and

dynamics, plasma column rotation, neutral penetration inside the plasma column, Hα emission

during gas-puffs, carried out in ADITYA/ADITYA-U tokamak using spectroscopic

measurements and modelling will be presented.

*Contributions from: M. B. Chowdhuri, Ranjana Manchanda, Ritu Dey, A. Bhattacharya, Nandini

Yadava, G. Shukla, Kajal Shah, Sharvil Patel, Nilam Nimavat, Ketan Patel, S. Banerjee, Vinay Kumar,

P. Vasu, and ADITYA/ADITYA-U team.

mailto:[email protected]


IT-08

Photoionization studies of argon inside charged fullerene

Afsal Thuppilakkadan1, 2 Jobin Jose and Hari R. Varma1*

1 School of Basic Sciences, IIT Mandi, Kamand 175075, Himachal Pradesh 2 Department of Physics, IIT Patna, Bihta-801103, Bihar, India

*[email protected]

Photoionization studies of confined atomic systems such as atom inside fullerene (A@C60)

continue to attract attention across scientific community owing to its importance in various

research fields. An outstanding feature of the ionization spectrum of confined atomic systems

is the presence of confinement resonances emerging from the interference between the

outgoing photoelectron wave and the reflected wave from the confinement well. A number of

studies have been reported discussing various features of such resonances and its consequences

on various photoionization parameters [1, 2]. Earlier theoretical studies on Ne@C60q, q being

the charge on fullerene, have shown the appearance of a different type of confinement

resonances, known as Coulomb confinement resonances, appearing on the 1s ionization

spectrum due to the presence of charged fullerene [3, 4]. In the present work, we extend the

studies for the case of Ar@C60q to study such resonances and its impact on the photoionization

spectrum.

References[1] V. K. Dolmatov, adv. quantum chem. 58, 13(2009) and references therein

[2] Subhasish Saha, Afsal Thuppilakkadan, Hari R Varma, Jobin Jose, J. Phys. B 52, 145001 (2019) and

reference therein.

[3] V. K. Dolmatov, S. T. Manson, Phys. Rev. A 73, 013201 (2006).

[4] A. Kumar, H. R.Varma, P. C. Deshmukh, S. T. Manson, V. K. Dolmatov, A. S. Kheifets, Phys. Rev. A 94,

043401 (2016).


IT-09

Shannon’s entropy in endohedrally confined atoms: Indicator of avoided

crossing and correlation energy

Jobin Jose1*

1 Department of Physics, Indian Institute of Technology Patna, Bihta, Patna 801103

*[email protected]

Shannon’s entropy is an indicator of localization of electronic density [1]. The electronic

density of confined atom has been investigated using Shannon’s entropy as a probe parameter

[2, 3]. Sensitivity of Shannon’s entropy with variation of confinement strength unveiled its

profile near the avoided crossings in endohedral atoms [4]. Objective of the present work are

two fold: (1) To understand the sensitivity of Shannon’s entropy to different confinement

potentials in the avoided crossing region and (2) To address the variation in Shannon’s entropy

with many-electron correlation energy.

To accomplish the first objective, Shannon’s information entropy of the ground state and some

of the excited states of confined H atom as a predictor of avoided crossing is studied. This is

achieved by varying the strength of the confinement and examining structure properties like

ionization energy and Shannon’s information entropy. Along with the energy level repulsion

at the avoided crossing, Shannon’s information entropy is also exchanged between the

involved states. The reciprocity relation of entropy in the radial and momentum space

consequent to the Heisenberg’s uncertainty relation is scrutinized in parallel.

Towards understanding the entropy difference due to the many-electron correlations in

confined atoms, correlation energy of Be@C60 and Mg@C60 have been investigated using

modified Dirac-Fock (DF) and multi-configuration Dirac-Fock (MCDF) methods. These

calculations are done using the grasp92 suit of codes [5]. A term-Correlation entropy is

defined, sensitivity of which is studied with varying confinement strengths.

Endohedral systems in the present work is approximated using two spherically symmetric

potentials: hard Annular Square Well (ASW) and smooth Gaussian Annular Square Well

(GASW) [6]. Sensitivity of Shannon’s entropy to the choice of potentials is employed to look

for a realistic confinement potential.

References [1] C.E. Shannon, Bell Syst. Tech. J. 27, 379 (1948).

[2] W. S. Nascimento , F. V. Prudente, Chem. Phys. Lett. 691, 401 (2018).

[3] L. G. Jiao, L. R. Zan, Y. Z. Zhang, Y. K. Ho, Int. J. Quantum Chem. 117, 25375 (2017).

[4] D. M. Mitnik, J. Randazzo, G. Gasaneo, Phys. Rev. A 78, 062501 (2008).

[5] F. A. Parpia, C. Froese Fischer, I. P. Grant, Comp. Phys. Comm. 94, 249 (1996).

[6] Subhasish Saha et al., J. Phys. B: At. Mol. Opt. Phys. 52, 145001 (2019).


IT-10

Laser cooling and trapping of Rb at narrow blue transition

Dangka Shylla1, Elijah Ogaro Nyakang'o1, Rajnandan Choudhury Das1 and Kanhaiya

Pandey1*

Indian Institute of Technology, Guwahati

*[email protected]

The temperature of magneto-optical trap (MOT) is limited by the linewidth of the transition.

Rb is commonly cooled and trapped using 5S1/2 → 5P3/2 at 780nm (IR) transition. The linewidth

of this transition is 2π⋇6 MHz which limits the temperature of the MOT to be 150 μK. The

linewidth of the other transition, 5S1/2 → 6P3/2 at 420 nm (blue) is 2π⋇1.2 MHz which is 5 times

narrower than the 5S1/2 → 5P3/2 and hence expected to provide lower temperature by 5 times.

In this talk, we present details of our experiment including spectroscopy and loading the Rb

atoms in blue MOT.



IT-11

Precision quantum measurements using optical clock

Subhadeep De

Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune

411007, India.

*[email protected]

At IUCAA, we have recently started to set up the Precision Quantum Measurement-lab (PQM-

lab) that aims to develop quantum enhanced technologies to support national missions as well

as to pursue precision atomic spectroscopy for probing fundamental sciences. The PQM-

facility shall comprise of a trapped ytterbium-ion (Yb+) optical clock for absolute optical

referencing, ultra-stable Fabry-Perot (FP) cavity that acts as a steady flywheel oscillator,

stabilized optical frequency comb to generate the photons at the desired wavelengths and phase

stabilized link-fiber via bi-directional communication through it. Such a system will facilitate

long distance precise intercomparison of the optical photons and can be utilized to stabilize

various other sources with respect to a standard optical reference. We plan to develop the

optical atomic clock based on the ultra-narrow 4f146s 2S1/2 - 4f136s2 2F7/2 electric octupole (E3)

transition at 467 nm wavelength of Yb+. Upon commissioning, this facility will produce phase

& frequency stabilized narrow-linewidth and ultra-stable optical reference source, which is

requisite for state-of-the-art instruments and high-end technologies, namely, Laser

Interferometer Gravitational-Wave Observatory (LIGO) and quantum communication,

respectively. Other than these applications, the PQM-facility will be used for variety of

precision measurements such as, geodesy, probing temporal constancy of the dimensionless

fundamental constants, quantum metrology and so on. An overview of this planned activity

together with possible applications of it will be presented in the meeting.



IT-12

Spectroscopic constants and thermochemistry of some

ozone depleting systems

T. K. Ghosh

Department of Physics

Diamond Harbour Women’s University, Sarisha, WB, India


In the atmosphere, particularly in the lower stratosphere region, ozone plays a vital role in

protecting harmful ultra-violet (UV) radiation in reaching to our earth and thereby decreases

several hazardous effects on human life and civilization like sunburn, skin cancer, global

warming, effects on earth’s environment, impact on vegetation, etc. Several natural occurring

processes, preservation processes and factory outlets contain Chlorofluorocarbons (CFCs) and

other compounds containing halogens (Cl, Br or I), generally grouped as Ozone Depleting

Substances (ODS). These ODS chemically react with the ozone available in the stratosphere

and thereby deplete the ozone layer.

It has been found that halogen oxides play an important role in such ozone depletion, viz.

IO + XO → I + X + O2 (X = Cl, Br)

I + O3→ IO + O2

X + O3→ XO + O2

Net: 2 O3→ 3 O2

These reactions may proceed through different channels, like

IO + XO → X + OIO (X = Cl, Br)

→ I + XOO → I+X+O2

→ IX + O2

→ I + OXO

However, experimental investigations on these systems are available, theoretical investigations

are limited. The geometry and spectroscopic properties of particularly XOO and XOO

molecules are still speculative.

The present report is focused on the spectroscopy of some molecules important in ozone

depletion. Ab initio calculations have been done to investigate geometry, spectroscopic

constants and thermochemical data of the reactants, products, various minimum energy

geometries and transition state geometries formed in course of the reactions. IRC calculations

are also to be reported for the reaction pathways of the different channels. The data may be

helpful in understanding their effectiveness in ozone depletion as well as may serve as future

references.

References [1] S. Solomon, R.R. Garcia and A.R. Ravishankara, J. Geophys. Res. 99, 20491 (1994).

[2] World Meteorological Organization/United Nations Environment Programme (WMO/UNEP): Scientific

assessment of ozone depletion, Geneva, WMO Rep. 25, 1992.

[3] Gilles, M.K.; Turnipseed, A.A.; Burkholder, J.B.; Ravishankara, A.R; Solomon, S.J. J. Phys. Chem. A101,

5326 (1997).

[4] Guha, S., Francisco, J.S., J. Phys. Chem. A114, 4254 (2010).

------------------------------------------

Acknowledgement: This work is funded by DSTB, Govt. of WB under the Project No.

357(Sanc.)/ST/P/S&T/16G-26/2018.


IT-13

Electron impact low energy studies for Di-triatomic targets

M. Vinodkumar

1 V. P. & R. P. T. P. Science College, Vallabh Vidyanagar, Gujarat, India

*[email protected]

Electron impact studies at low energy is very important since it involves elastic and distinct

inelastic processes such as discrete electronic excitations, dissociative electron attachment,

ionization etc. Each of the inelastic processes is very important especially at low energy since

it involves complex physics and helps us to understand many phenomenon such as resonance,

fragmentation, dissociation, recombination etc. In particular, the Dissociative electron

attachment processes occur in many applied fields such as gas discharges, plasmas, biological

systems, astrophysical environment as well as in atmosphere [1].

In the present work, I will discuss mainly dissociative electron attachment (DEA) cross

sections for Di-tri atomic targets along with other inelastic processes. DEA is a low energy

phenomenon generally below ionization threshold of the target where incoming electron

temporarily gets attached to the target molecule to form transient negative ion (TNI). The TNI

is a short lived state of the order of picoseconds or femtoseconds. The TNI either auto- detaches

or it decays leading to anionic fragments. Since the anionic fragment is a charged particle it

can be detected by conventional mass spectrometry, hence it is subject of great importance

experimentally. Moreover, theoretically the DEA process can be well understood by studying

the potential energy surface of neutral as well as anionic as fragment [2]. We employ R-matrix

formalism [3, 4] for computing discrete electronic excitations, and resonance width and

position by fitting them to Briet Wigner profile using RESON program. It has been observed

that DEA cross sections for halogen molecules are strongest [2, 5] and will be presented during

the conference.

Acknowledgement: Dr. Minaxi Vinodkumar acknowledges DST-SERB, New Delhi for major

research project [EMR/2016/000470] for financial support under which part of this work is carried out.

References [1] I. Fabrikant, S. Eden, N. Mason, J. Fedor, Adv. At., Mol., Opt. Phys. 66, 545-657 (2017)

[2] N. Mason, B. Nair, S. Jheeta & E. Szymańska, RSC Adv 168, 235-247 (2014).

[3] J. Tennyson, Phys. Rep. 491, 29 (2010)

[4] M. Vinodkumar, H. Desai, P. Vinodkumar. RSC Adv 5(31), 24564 (2015)

[5] H. Yadav, M. Vinodkumar, C. Limbachiya, P. C. Vinodkumar, J. Phys. B: At. Mol. Opt. Phys. 51, 045201

(2018).


IT-14

Application of plasma produced nanostructures in surface wettability and

sensing

M. Ranjan1,2, V. Pachichigar 1,2, Sooraj KP1 and S. Augustine1,2

1Institute for Plasma Research, Gandhinagar-382428, India 2Homi Bhabha National Institute, Mumbai-400094, India


Low energy Ar ion irradiation leads to regular nanoripples and nanodots like structures on the

surfaces. Properties of such nanostructures can be tailored by ion energy, incidence angle and

ion dose [1, 2]. In the recent past such nanostructures found applications in plasmonics and

magnetism [1, 2]. In the current work, I shall be showing how PTFE surface become

superhydrophobic in just few seconds ion irradiation in the ion energy range 300 eV to 800 eV

[3]. The surface morphology revealed the formation of hierarchical micro and nanostructures

on its surface. Detailed wetting behaviour of irradiated PTFE was studied using contact angle,

surface free energy and rolling speed measurement. A systematic increase in the contact angle

was observed with increase in ion energy, irradiation time and surface roughness. After a

threshold irradiation time, the water droplet started rolling from the horizontal surface in each

ion energy range. The self-cleaning property of this superhydrophobic PTFE was effectively

achieved by conducting dust removal test with carbon powder.

In the later part, I will discuss how plasma produced nanoripple patterns can be used as a

template for growing highly ordered nanoparticles [1, 2]. These nanoparticle arrays can show

strong surface plasmon resonance whose spectral position depends on the polarization of

incident light. We have shown that the plasmon resonance of silver nanoparticle arrays grown

on ripple patterned templates can be tuned by changing the ripple periodicity/aspect ratio and

Surface Enhanced Raman Scattering (SERS) intensity can be optimised with these parameters

[4,5]. SERS based detection of glucose deposited on ion beam produced ripple patterned

substrate with silver nanoparticle arrays will be reported for concentrations 5x10-2 g/ml,

5x10-3 g/ml, 5x10-4 g/ml and 5x10-5 g/ml without using binder molecule. These concentrations

are relevant to blood glucose level [4,5]. A comparative study of detection of Glucose

deposited on plane Si substrate, Plane Si substrate with silver nanoparticles and patterned Si

substrate with Silver nanoparticles will be reported. Due to larger enhancement of nanoparticle

chain, we could detect Glucose without the binder molecule for much lower concentrations.

Some preliminary study conducted on breast cancer cell detection and blood plasma will also

be presented using above mental nanoparticles.

Reference [1] M. Bhatnagar, M. Ranjan, R. Smith, S. Mukherjee, Applied Physics Letters 108, 223101 (2016).

[2] M. Ranjan, M. Bhatnagar, S. Mukherjee, Journal of Applied Physics 117, 103106 (2015).

[3] V. Pachchigar, M. Ranjan, S. Mukherjee, Scientific Reports 9, 8675 (2019).

[4] M. Arya, M. Bhatnagar, M. Ranjan, S. Mukherjee et al., Journal of Physics-D 50, 455603 (2017).

[5] Sooraj K P, M.Ranjan, R.Rao, S. Mukherjee, Applied Surface Science 31. 576 (2018).


IT-15

Study of nonlinear waves in multicomponent space plasmas

N. S. Saini

Guru Nanak Dev University, Amritsar-143005, India

Over the past many years, the dense quantum plasmas have been the focus of many researchers

because of its wide ranging applications in different fields such as semiconductor devices [1],

metallic nano-structures [2], and astrophysical objects [3]. The particles with quantum nature

have a great influence on the macroscopic properties of such type of plasmas. The de-Broglie

wavelength of the charge particle is comparable to the inter-particle distance and Fermi

temperature exceeds the system temperature in quantum plasma. In such situations, the

quantum mechanical effects play very important role in the dynamics of charged particles and

the plasma particles behave like Fermi gas [4]. The quantum tunneling effects are also taken

into account by considering the Bohm potential term in the corresponding momentum

equations of degenerate electrons. The ion- acoustic waves (IAWs) are among the most well

studied electrostatic modes in both linear and nonlinear regimes in dense astrophysical

plasmas. In the present talk, the influence of various plasma parameters on the nonlinear

dynamics of ion acoustic excitations (solitons, periodic waves and other kinds of nonlinears

structures) have been investigated in a dense magnetized plasma by employing the spin-

evolution quantum hydrodynamic model. The plasma model composed of degenerate

electrons having both spin-up and spin-down states as well as non-degenerate cold ions. The

Korteweg-de Vries (KdV) equation is derived using the reductive perturbation technique and

solved numerically to investigate the characteristic features of nonlinear structures. The family

of the KdV equation is used to describe a non-modulated wave, which is usually called the

KdV solitons, while the nonlinear Schrödinger equation (NLSE) describes the dynamics of the

nonlinear modulated waves. In this talk, the nonlinear Schrödinger equation is described to

study the characteristics of different order rogue waves [5]. The parametric role of the spin

density polarization ratio on the amplitude and width of nonlinear structures and rogue waves

is also investigated. The numerical results obtained in the present investigation may be

applicable to high density astrophysical regions such as white dwarfs and can also be helpful

in understanding the properties of compact astrophysical objects where degenerate electrons,

light nuclei and heavy nuclei are available.

Reference

[1] M. C. Yalabik, G. Neofotistos, K. Diff, H. Guo, and J. D. Gunton, IEEE Trans. Electron

Devices 36, 1009 (1989).

[2] J. Y. Bigot, J. Y. Merle, O. Cregut, and A. Daunois, Phys. Rev. Lett. 75, 4702 (1995).

[3] S. L. Shapiro and S. A. Teukolsky, Black Holes, White Dwarfs, and Neutron Stars—The

Physics of Compact Objects (Wiley-VCH, Weinheim, 2004).

[4] G. Manfredi, Fields Inst. Commun. 46, 263 (2005).

[5] N. Kaur and N. S. Saini, Astrophys. Space Sci. 336, 331 (2016)


IT-16

Strong field ionization with ultrashort orbital angular momentum

beams

R. Gopal1*, A. Sen2, A. Sinha3 and V. Sharma1

1 Tata Institute of Fundamental Research, Hyderabad 2 Indian Institute of Science Education and Research, Pune

3Indian Institute of Technology, Hyderabad

*[email protected]

Finite light beams with an azimuthal dependence of the phase over the beam are said to possess

an orbital angular momentum (OAM), which can be generated through holograms, spiral plates

or ring resonators etc. Light-matter interaction with these beams raises a fundamental question

on the nature of transfer of this property of light to matter [1]. In experiments so far, only with

macroscopic systems, has the OAM of the light beam manifested. In this talk, I will describe

our experiments on the photoionization with linearly polarized, ultrashort (25 fs) intense (1013-

1014 W/cm2) laser pulses endowed with a definite OAM (l =1). Photoionization with these laser

pulses is through non-resonant multi-photon processes or tunnel ionization through the

suppression of the Coulomb barrier of the atom. Three-dimensional angular distributions of

the singly ionized electron is captured through a newly commissioned ‘Reaction Microscope’

[2]. Through careful experimentation it appears that no transfer of the angular momentum of

the beam to the ionized electron occurs, at least, in these strong-field single atom-laser

interaction conditions.

References [1] A. Picon et al., New Journal of Physics 12, 083053 (2010).

[2] J. Ullrich et al., Rep. Prog. Phys. 66, 1463-1545 (2003).


IT-17

Diagnostic of non-thermal atmospheric pressure plasma jet through

emission and absorption spectroscopy

R. K. Gangwar1,*, P S Srikar1 and S M Bakshi2

1Department of Physics, Indian Institute of Technology Tirupati, Tirupati 517506, AP, INDIA 2Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Tirupati 517506, AP,

INDIA

*[email protected]

Non-thermal plasma jets at atmospheric pressure are receiving significant attention from the

scientific community [1]. A major part of motivation comes from the fact that the plasma jet

can produce a significant amount of reactive species (oxygen or nitrogen-based) at room

temperature. This makes them very suitable candidates for a wide range of applications such

as cancer therapy, wound healing, sterilization, material processing, mass-spectrometry and

many more. However, in order to establish these plasma sources as a viable solution, the

detailed diagnostic is a prime requirement. The non-thermal atmospheric pressure plasma jet

(NTAPJ) is normally very small in dimension and exhibits a very high gradient of plasma

species. This restricts the application of traditional plasma diagnostic approaches such as a

Langmuir probe. Further, the laser scattering based approaches could be useful but they are

very expansive and also not very portable. Besides, the implementation is not very straight

forward. The optical emission spectroscopy-based approaches can provide a very suitable

solution for diagnostic studies. However, due to the non-equilibrium nature of the plasma, the

extraction of plasma parameters from these measurements requires the development of the

population-kinetic models. The development of the population-kinetic model is also very

challenging as plasma operates in ambient air. This requires the inclusion of a large number of

reactions of plasma species with the molecules present in the air. In order to resolve these

issues, we recently implemented a hybrid approach by combining the absorption and emission

spectroscopy measurements. Under this scheme, a simpler collisional radiative model can

extract reliable information from the measurement. During my talk, I shall present the details

of the approach along with the diagnostic that was carried on an Ar atmospheric pressure

plasma jet.

Reference [1] S. Reuter et al., The kINPen—a review on physics and chemistry of the atmospheric pressure plasma jet and

its applications, Journal of Physics D: Applied Physics 51, 233001 (2018).



IT-18

Multidiagnostic characterization of ultrashort and short pulse laser

produced plasmas

Pranitha Sankar and Reji Philip

Raman Research Institute Sadashivanagar, Bangalore 560080

The field of laser produced plasmas (LPP) has greatly attracted the research community

because of its wide range of applications such as pulsed laser deposition, generation of light

sources and ion beams, plasma-based acceleration etc. In this talk we discuss space and time-

resolved studies of plasmas produced by ultrashort (100 fs) and short (7 ns) laser pulse ablation

of Aluminium (Al) and Tungsten (W) targets, kept at different ambient pressures ranging from

10-5 to 760 Torr. Optical time of flight spectroscopy (OTOF), optical emission spectroscopy

(OES), time-resolved ICCD imaging, and ion dynamics studies have been carried out in these

plasmas. Electron temperature and number density have been calculated from the optical

emission spectra.

Figure 1: Different processes in laser ablation in their respective timescales, spanning the range

of femtoseconds to milliseconds.

The intensities of the plasma plumes as well as the relative abundance of the ions are found to

be different between ultrashort laser ablation (ULA) and short laser ablation (SLA), because

of differences between laser-target and laser-plasma interactions. OTOF measurements, time-

resolved ICCD imaging and ion emission measurements reveal the presence of both fast

moving as well as slow-moving species in SLA, while this distinction is not equally obvious

in ULA. Linear, shock wave and drag models are used to model plume and ion dynamics in

the low, intermediate and high-pressure regions respectively. In addition, the expansion

dynamics of the ULA aluminum plasma is investigated as a function of the laser beam size on

the target, using a combination of the above-mentioned diagnostic tools. Optical emission


spectroscopic analysis shows that higher emission intensities and ion populations can be

obtained for smaller beam sizes. Time-resolved ICCD imaging of the expanding plasma shows

a spherical morphology for plumes produced by smaller beam sizes, and a cylindrical

morphology for those produced by larger beam sizes. A comprehensive comparison of X-ray

emission from ULA and SLA plasmas also has been carried out. These results will be discussed

in this talk.

Figure 2: Experimental setup for the multidiagnostic characterization of laser produced

plasmas.


IT-19

Neutrino-plasma interactions in gravitating degenerate astrophysical

plasmas

R. P. Prajapati

Dept. of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur 495009 (C.G.)

*[email protected]

The neutrinos are weakly interacting particles with plasma constituents and play a crucial role

in the energy transfer between the neutrino beam and the plasma in the supernova core-

collapse. The physics of collective neutrino-plasma interactions and excitation of plasma

turbulence by a large neutrino flux has been discussed in many problems [1, 2]. In this work,

the interactions of arbitrarily propagating energetic neutrino beam with dense magnetized

degenerate quantum plasma has been studied. The neutrino magnetohydrodynamic (NMHD)

model is formulated considering the effects of quantum in the ideal quantum

magnetohydrodynamic (MHD) plasma. The theoretical model establishes the interplay

between weak interacting neutrinos and magnetized quantum plasma. The general dispersion

relation is derived and neutrino beam driven instability is analyzed in the supernova core-

collapse. It is observed that quantum corrections significantly modifies the growth rate of

neutrino beam instability. The neutrino beam density and quantum corrections decrease the

critical Jeans wavenumber of perturbations, below which the system becomes gravitationally

unstable. The time scale of the neutrino beam is too short as compared to the Jeans time scale

which causes a faster mixing of the neutrino beam in the gravitational collapse of supernova.

The neutrino beam energy destabilizes the growth rate of the Jeans instability in the core-

collapse [3].

This work is also applicable to understand the neutrino-beam-plasma interactions in the

crust of neutron stars and magnetars considering magnetic field well below the Schwinger limit

so that the nonlinear effects and electron-positron pair creation can be safely ignored in

quantum electrodynamics (QED) [3].

References [1] F. Haas, K. A. Pascoal, and J. T. Mendonca, Phys. Plasmas 23, 012104 (2016).

[2] F. Haas, K. A. Pascoal, and J. T. Mendonca, Phys. Rev. E 95, 013207 (2017).

[3] R. P. Prajapati, Phys. Plasmas 24, 122902 (2017).


IT-20

Gas-phase formation of ammonia in the diffuse interstellar medium

calculation of the rate coefficients of the key steps

Sunil Kumar S1,∗, Salvi M1 and Raghunath O. Ramabhadran2

1Department of Physics, IISER Tirupati, Tirupati - 517507, Andhra Pradesh, India 2Department of Chemistry, IISER Tirupati, Tirupati - 517507, Andhra Pradesh, India

∗[email protected]

Ammonia, one of the most important molecules relevant to the ecosystem on earth, was the

first nitrogen-bearing molecule detected in the interstellar medium (ISM) [1, 2]. However, the

formation mechanisms of ammonia in the diffuse ISM is still not completely understood.

Currently, the pathway proposed [2] to occur in gas-phase in the diffuse ISM in producing

NH3 is as follows:

𝑁+ + 𝐻2 → 𝑁𝐻+ + 𝐻 (1)

𝑁𝐻+ + 𝐻2 → 𝑁𝐻2+ + 𝐻 (2)

𝑁𝐻2+ + 𝐻2 → 𝑁𝐻3

+ + 𝐻 (3)

𝑁𝐻3+ + 𝐻2 → 𝑁𝐻4

+ + 𝐻 (4)

𝑁𝐻4+ + 𝑒− → 𝑁𝐻3 + 𝐻 (5)

In this work, the third and fourth of the above reactions were analyzed theoretically using variational transition state theory (CVT); the latter was addressed recently by Alvarez et al. [3]. The rate coefficients of the third reaction as a function of temperature ranging from 10 to 300 K was determined using variational transition state theory and the results (Fig. 1) were found to be in reasonable agreement with recent experimental results [4]. These two reactions are found to be exothermic and feature a small activation barrier which essentially is a consequence of the zero-point energy corrections. The results demonstrate that quantum mechanical tunneling plays a key role in the formation of ammonia in the ISM (T < 100 K).

Figure 1: The rate coefficients of the reaction between NH2

+ and H2 as a function of temperature. The calculations were made at two levels of theory, MP2 and CCSD with basis set aug-cc-PVTZ. The thin lines are results from CVT calculations without tunneling. The results marked with legends “Wigner” and “Eckart” represent the rate co-efficients that include Wigner and Eckart tunneling corrections respectively.

References [1] Herbst, E., DeFrees, D. J. & McLean, A. D., Astrophys. J. 321, 898 (1987).

[2] Le Gal, R. et al., Astron. Astrophys. Suppl. Ser. 562, A83 (2014).

[3] A lvarez-Barcia, S., Russ, M.-S., Meisner, J. & Kastner, J., Faraday Discuss. 195, 69 (2017).

[4] Rednyk, S. et al., Astron. Astrophys. Suppl. Ser. 625, A74 (2019).



IT-21

Atom-optic kicked rotor: From quantum chaos to atom interferometry

Umakant Rapol*

Department of Physics, Indian Institute of Science Education and Research Pune-411008

*[email protected]

In this talk I will present our recent work using an Atom-Optic Kicked Rotor (AOKR) with

ultracold atoms and Bose-Einstein Condensate.

AOKR is a rich experimental test bed for simulating the physics of classically chaotic

quantum systems. Using AOKR we show that one can engineer the 'Thermal Bath" to which

quantum systems couple and decohere. Decoherence can be prolonged by appropriately

engineering the bath. In particular, we show that one can make the system decohere in such a

manner that it deviates from an exponential to power law a function of time. In addition, we

also show that the system shows an optimal diffusion under specific conditions of the bath. In

the second part of the talk, a variation of the AOKR on a BEC can be used to study and use the

Talbot effect for building an Atom Interferometer.


IT-22

Photodissociation and dissociative electron attachment: similarities and

differences

V. S. Prabhudesai1*

1 Tata Institute of Fundamental Research, Mumbai 400005 India

*[email protected]

Dissociative electron attachment (DEA) is one of the most important processes that occurs

when low energy electron (< 20 eV) interacts with molecule. The process involves capture of

low energy electron resulting in the formation excited anion state also called a negative ion

resonance (NIR) and its subsequent dissociation. This process competes with the electron

ejection also known as autodetachment. These NIR states are always described in terms of the

corresponding neutral ground or excited state also called the parent state for the NIR. On

similar lines, in photodissociation, the photon is absorbed by the molecule resulting in its

excitation which is followed by dissociation.

Although both the processes involve molecular excited states, the presence of additional

electron makes dynamics of the NIR state in DEA much richer than that of neutral excited state

in photodissociation. In this talk, I will describe two such cases where we have encountered

the similarities as well as differences in these processes that highlight the interesting aspects

of DEA.


IT-23

Foam structure of dopants in helium nanodroplets? Some evidences in

photoionization of acetylene doped helium droplets

Suddhasattwa Mandal1, Ram Gopal2, M. Shcherbinin3, Robert Richter4, H. Srinivas4,

Marcello Coreno4, Alessandra Ciavardini4, A D’Elia5, B Bapat1, M Mudrich3, S. R.

Krishnan6 and V. Sharma7*

1 Indian Institute of Science Education and Research Pune, Pune – 411008, Maharashtra, India 2 Tata Institute of Fundamental Research Hyderabad, Hyderabad – 500107, Telangana, India

3 Aarhus University, 8000 Aarhus C, Denmark 4 Elettra-Sincrotrone Trieste, Strada Statale 14-km 163.5, 34149 Basovizza, Trieste, Italy

5 University of Trieste, Department of Physics, 34127 Trieste, Italy 6 Indian Institute of Technology Madras, Chennai – 600036, Tamil Nadu, India

7 Indian Institute of Technology Hyderabad, Sangareddy – 502285, Telangana, India *[email protected]

The impact of environment in the fragmentation dynamics of small molecules remains an

intriguing object of investigation wherein the dynamics of these systems embedded in Helium

nanodroplets generally gets modified. We have performed an experiment at Elettra Synchrotron

Facility at Trieste wherein we doped Helium nanodroplets with acetylene molecule. Acetylene

molecule being heliophilic embed inside the nanodroplet. Here, we studied the ionization of

acetylene through the relaxation of photoexcited Helium nanodroplet. This is a well-known

Penning process. In the current work, we demonstrated that the ionization of acetylene molecule

through Penning process is not limited only to the n=2 droplet excitation but is also extended to

higher excitation bands of droplet such as n=4. Employing the spectroscopic techniques, we also

revealed the oligomer formation of acetylene inside Helium nanodroplets. The acetylene molecules

coalesce in the form of loosely bound van der Waals aggregates, called as foam-like [1] structure.

This structure collapses into a composite oligomer ion following Penning ionization [2]. A detailed

experimental investigation will be presented during the talk.

References [1] S Göde, R Irsig, J Tiggesbäumker, K-H Meiwes-Broer, New. J. Phys, 15, 015026 (2013)

[2] S. Mandal et al [under preparation]


IT-24

Accurate calculation of weak intermolecular interaction energy

Narendra Nath Dutta

Department of Chemical Sciences, Indian Institute of Science Education and Research Mohali,

Punjab-140306, India

An accurate potential energy surface due to weak interaction or noncovalent interaction

between two molecules to form a supermolecule is very much important in the study of binding

and folding of a biological complex [1], in the analysis of a molecular scattering experiment

[2] and also in the molecular spectroscopy [3]. Though several variants of electron density

based methods [4] are relatively much popular tools to compute such surfaces, their reliability

can be questioned in many situations. An alternative way to compute such a potential energy

surface can be to use a suitable wavefunction based method [1]. Here we show two of such

methods: an explicitly-correlated coupled-cluster method [5] with added bond functions [6]

for closed-shell systems and a multireference version of symmetry-adapted perturbation theory

(MRSAPT) [7, 8] for open-shell systems. The former can calculate the interaction energy by

subtracting the sum of the individual energies of the two molecules from the total energy of

the supermolecule: ∆E = EAB - (EA + EB) with A and B indicating the two molecules. Very

recently, we recommend a variant of explicitly-correlated coupled-cluster methods with added

bond functions (CCSD(Tbb)-F12b/aug-cc-pVDZ+(3s3p2d2f)) which has a potentiality to

calculate the interaction energy at the geometrical equilibrium with mean unsigned error within

0.05 kcal/mol of basis set limit [9]. Here the mean is calculated by computing the interaction

energies of 46 supermolecular species of di_erent sizes ((HF)2 dimer to adenine-thymine

complex). The extension of this work for the entire potential energy surface is a future plan to

be carried out. The latter method, MRSAPT, which is currently under development [8],

considers the weak interaction as a perturbation to a supermolecule consisting of two non-

interacting molecules. The advantage of MRSAPT or in fact any version of SAPT [7] is that it

not only computes the interaction energy accurately, but also can decompose this energy in

terms of its physical components: electrostatic, induction, and dispersion along with their

exchange counterparts. Therefore, the SAPT or MRSAPT depicts the picture of relative

strengths among these components at various regions of a potential energy surface.

Acknowledgement: A thankful gratitude to Dr. Konrad Patkowski, Auburn University, USA

to work as an advisor and a coordinator to carry out these works.

References [1] E. G. Hohenstein, and C. D. Sherrill, WIREs Comput. Mol. Sci. 2, 304 (2012)

[2] V. Aquilanti, and D. Ascenzi, J. Chem. Phys. 109, 3898 (1998)

[3] I. I. Mizus et al., Phil. Trans. R. Soc. A 376: 20170149 (2018)

[4] W. Koch, and M. C. Holthausen, A Chemist's Guide to Density Functional Theory, (Wiley-VCH, 2000)

[5] G. Knizia, T. B. Adler, and H.-J. Werner, J. Chem. Phys. 130, 054104 (2009)

[6] F. -M. Tao, J. Chem. Phys. 100, 3645 (1994); Int. Rev. Phys. Chem. 20, 617 (2001)

[7] K. Szalewicz, WIREs Comput. Mol Sci. 2, 254 (2012)

[8] N. N. Dutta, D. G. A. Smith, and K. Patkowski, Towards Multireference Symmetry-Adapted Perturbation

Theory, Presented in SETCA-2017 at University of Mississippi, USA

[9] N. N. Dutta, and K. Patkowski, J. Chem. Theory Comput. 14, 3053 (2018)


IT-25

Electron induced ionization cross sections of atoms, ions and molecules

relevant to plasma applications

Ghanshyam Purohit1* and Daiji Kato2,3,4

1Department of Physics, University College of Science, Mohanlal Sukhadia University, Udaipur-

313001, India 2National Institute for Fusion Science, National Institutes of Natural Sciences 322-6 Oroshi-cho, Toki

Gifu, 509-5292, Japan 3Department of Fusion Science, SOKENDAI, 322-6 Oroshi-cho, Toki Gifu, 509-5292, Japan

4Department of Advanced Energy Engineering Science, Kyushu University,Kasuga Fukuoka, 816-

8580, Japan

*[email protected], [email protected]

Ionization of targets such as atoms, ions, and molecules by charged projectiles such as

electrons/positrons has been studied from a long time and has various applications; few may

be listed as diagnostics of fusion plasmas, modeling of physics and chemistry related to

atmosphere, understanding the effect of ionizing radiation on biological tissues etc. The

ionization cross sections are essential in the modeling of plasma in fusion research. Beryllium

(Be) is one of the materials which is directly exposed to the plasma components in the

International Thermonuclear Experimental Reactor (ITER) [1]. Formation of gas-phase Be in

various charge states and of hydrides of Be, takes place when the erosion of Be walls occurs

in contact with the hot plasma containing hydrogen and its isotopes. Electron collision

processes on the beryllium and its charged states play an important role in the fusion edge and

diverter plasmas. The tungsten (W) and tungsten based materials have also been recommended

as one of the materials to be used as plasma facing components for the International

Thermonuclear Experimental Reactor (ITER) [1], and it is also been used in the number of

current tokamaks such as JET, ASDEX-Upgrade and DIII-D. Electron induced processes are

prevalent in such magnetic fusion devices in a wide range of energies.

We report the results of our recent work on calculation of electron impact ionization cross

sections for Be, W atoms, charged states of Be and W [2-4] and BeH. The status of charged

particle ionization processes from targets with introductory idea about the theoretical

formalism involved will be reviewed and results for the electron impact ionization of

atomic/ionic/molecular targets will be discussed.

References:

[1] G. Federici, Phys. Scr. T 124, 1 (2006).

[2] G. Purohit and D. Kato, J. Chem. Phys. 148, 084307 (2018).

[3] G. Purohit, D. Kato and I. Murakami, Plasma and Fusion Research 13, 3401026 (2018).

[4] G. Purohit and D. Kato, J. Phys. B: At. Mol. Opt. Phys. 51, 135201 (2018).


PP-01

Gravitational instability of rotating plasma with radiative heat-loss

function and FLR corrections

Sachin Kaothekar1* and R. K. Chhajlani2

1 Department of Physics Mahakal Institute of Technology and Management, Ujjain-456664, (M.P.),

India 2 Retired Professor School of Studies in Physics Vikram University, Ujjain-456010, (M. P.

*email address of the corresponding author:[email protected]

The effect of finite ion Larmor radius (FLR) corrections and rotation on the gravitational

instability and radiative instability of infinite homogeneous plasma has been explored

integrating the consequences of radiative heat-loss function and thermal conductivity. The

general dispersion relation is obtained by means of the normal mode analysis scheme with the

help of appropriate linearized perturbation equations of the problem. These dispersion relations

are further discussed for rotation axis parallel and perpendicular to the magnetic field. Stability

of the medium is argued by applying Routh Hurwitz’s criterion and it is found that Jeans

criterion establishes the stability of the medium. We locate that the presence of radiative heat-

loss function and thermal conductivity amend the fundamental Jeans criterion of gravitational

instability into radiative instability criterion. Numerical computations have been executed to

show the effect of various parameters on the growth rate of the Jeans-gravitational instability.

We find that rotation, and FLR corrections steady the growth rate of the organization in both

the transverse mode and longitudinal mode or propagation. Our result demonstrates that the

rotation, and FLR corrections affect the dens molecular clouds configuration and star

formation.

References [1] S., Kaothekar, G. D., Soni, R. P., Prajapati and R. K., Chhajlani, Astrophys. Space Sci. 361, 204, (2016).

[2] J. S., Dhiman and R., Dadwal, Astrophys. Space Sci. 332, 373-378, (2011).


PP-02

Ionization cross sections of water molecules impacted by dressed ions

D. Jana1, A. Mondal2 and M. Purkait1*

1Department of Physics, Ramakrishna Mission Residential college, Narendrapur,

Kolkata-700103, India 2Department of Physics, Ramsaday College, Amta, Howrah-711401, India

*mpurkait [email protected]

The investigation of electronic reactions involved in collision between ions and molecules are

of relevance in many areas like plasma physics, astrophysics, medical physics and radio-

biology. In particular, in radiation biology, single electron ionization processes are the main

mechanisms leading to energy loss for swift ions penetrating the living matter at medium and

high impact energies. In the present work, we focus our research on single electron ionization

of water molecule by dressed ions impact using the three coulomb wave (3CW) model [1]. The

3CW model is used to study the variation of double-differential cross sections (DDCS) with

(i) electron emission angle at fixed emission energy and (ii) electron ejection energy at fixed

emission angle. Both the studies consider one electron of the target as active and treat others

to be frozen. Molecular orbital is expressed by linear combination of slater-type atomic orbitals

(STO) [1]. The transition amplitude in prior form is given as

𝑇𝑖𝑓 = ⟨𝜓𝑓|𝑉𝑖|𝜓𝑖⟩; (1)

The perturbation in the initial channel is given by

𝑉𝑖 = 𝑉𝑇𝑃(�� ) + 𝑉𝑃𝑒(𝑠 ); (2)

𝑉𝑃𝑒(𝑠 ) =𝑞

𝑠−

𝑒−𝜆𝑠

𝑠[(𝑍 − 𝑞) + 𝑏𝑠];

(3)

where, b and 𝜆 are variational parameters fixed by the diagonalizing the model Hamiltonian

of the active electronprojectile interaction with respect to Slater basis [2].

Figure 1: DDCS for single ionization as a function of electron emission angle for fixed value

of electron emission energy.

The authors gratefully acknowledge the financial support from the SERB, New Delhi, (No.

CRG/2018/001344).

References [1] A. Mondal, C. R. Mandal, M. Purkait, J. Phys. B: At. Mol. Opt. Phys. 49, 075201 (2016).

[2] M. Das, M. Purkait, C. R. Mandal, Phys. Rev. A 57, 3573 (1998).

[3] C. C. Dal et al., Nucl. Instrum. Methods Phys. Res. B 267, 781 (2009).

[4] C. A. Tachino et al, J. Phys B: At. Mol. Opt. Phys. 47, 035203 (2014).



PP-03

Atomic-size Fraunhofer-type diffraction for electron capture in

ion-atom collision

S. Samaddar, K. Purkait and M. Purkait*

Department of Physics, Ramakrishna Mission Residential College, Narendrapur,

Kolkata-700103, India *mpurkait [email protected]

The study of electron capture in ion-atom collisions have received a great deal of interest in

both fundamental and applied fields. On the applied side, these collisions are needed in

different fields; such as plasma physics, astrophysics, biophysics and fusion research.

Moreover, charge transfer in ion-atom collision provides much more information about the

fundamental studies of wave property of light which is nothing but diffraction. However, in

atomic collision studies, the interaction region of the target and the incoming projectile is

supposed to be a circular aperture. Thus the Fraunhofer-type diffraction is observed in the

projectile angular-differential cross sections. So the differential cross sections (DCS) for

electron capture is very much important to study the dynamics of ion-atom collision physics.

Recently, for the development of reaction microscope [1], that provides much more capture-

dynamics in different few-body ion-atom collision system by measuring the DCS with very

high precision. Motivated by this experiment, different theoretical models [2,3] have been

developed for understanding the capturedynamics. Therefore, in the center of mass frame, the

DCS for electron capture is given by

𝜎(𝜃𝑃, 𝐸) = (𝑑𝜎

𝑑Ω) =

𝜇𝑖𝜇𝑓𝑘𝑓

4𝜋2𝑘𝑖|𝑇𝑖𝑓

(±)|2,

(1)

and the TCS is given by

𝜎(𝐸) =𝜇𝑖𝜇𝑓𝑘𝑓

4𝜋2𝑘𝑖∫ |𝑇𝑖𝑓

(±)|2𝑑(cos 𝜃𝑃)

+1

−1

, (1)

Where 𝑇𝑖𝑓(±)

is the prior (-) or post (+) form of the transition amplitude and 𝜃𝑃is the projectile

cattering angle. The prior and post form of the transition amplitude may be written as

|𝑇𝑖𝑓(±)

| = ⟨𝜓𝑓−|𝑉𝑖,𝑓|𝜓𝑖

+⟩, (1)

where 𝜓𝑖+i is the initial state which is distorted by the incoming screened projectile.

Figure 1: DCS weighted by sinθ with the projectile scattering angle.

References [1] D. L. Guo et al, Phys. Rev. A 95, 012707 (2017).

[2] S. Halder, A. Mondal, S. Samaddar, C. R. Mandal, M. Purkait, Phys. Rev. A 96, 032717 (2017).

[3] J. W. Gao et al, Phys. Rev. A 97, 052709 (2018).


PP-04

VUV spectroscopy of ethyl methyl carbonate

A. K. Das1*, S. Krishnakumar1 and B. N. Rajasekhar1

1 Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085

*[email protected]

Green chemistry [1] promotes use of renewable raw material and energy resources for

production and synthesis of environment friendly biodegradable products and

prevention of waste. Ethyl methyl carbonate (EMC) comes under the category of

carbonate green solvents because of its clean production technology, non-toxicity and

biodegradability. EMC because of its low freezing point (-550C) finds application as

co-solvent in electrolytes used to enhance the low temperature performance of

rechargeable lithium ion batteries down to -400C. It is an asymmetric aliphatic

carbonate; the symmetric ones being dimethyl carbonate [2] and diethyl carbonate [3]

which too used as green solvents along with ethylene carbonate.

Considering the sparse spectroscopic data required for understanding the chemistry of

EMC with lithium ions, experiments have been carried out to obtain electronic excited

state information in gas phase. For this purpose, VUV photoabsorption spectrum of

EMC is recorded using monochromatic synchrotron radiation from Photophysics

beamline [4] at the Indus-1 synchrotron radiation source at RRCAT, Indore [5] in the

wavelength region 1050 Å-1800 Å. In addition, vibrational spectroscopy studies of

EMC are carried out in the 4000-500 cm-1 region to understand energetic of excited

states, energy ordering, assignment and nature of excited states etc. Geometry

optimization and vibrational frequency calculations of neutral and ionized EMC have

been carried out using density functional theory (DFT) method for a variety of basis

sets and correlation functional. The ground state equilibrium structure of EMC belongs

to CS point group. However, the lowest conformer of EMC is trans in nature whereas

for the two symmetric alkyl carbonates, cis-conformer was found to be stable. The

vertical and adiabatic ionization energies of EMC obtained from these simulations are

10.5 eV and 9.92 eV respectively. The highest occupied molecular orbital (HOMO) is

a non-bonding orbital on the oxygen atom of the carbonyl group whereas the lowest

unoccupied molecular orbital (LUMO) is of 3s Rydberg type. Time dependent DFT

(TDDFT) calculations have been performed for the analysis of electronic excited singlet

and triplet states. The valence excitation at 8.3 eV from HOMO-1 to an antibonding

orbital is of highest oscillator strength.

The experimental results and analysis of the VUV absorption spectrum will be presented

along with computational results performed using GAMESS (USA) [6].

References [1] P. T. Anastas, J. C. Warner. Green chemistry: theory and practice; Oxford University Press, New

York, London 1998. [2] A. K. Das, S. Krishnakumar, B. N. Rajasekhar, J Quant Spectrosc Radiat Transfer 217, 116 (2018).

[3] A. K. Das, B. N. Rajasekhar, S. Krishnakumar, J Quant Spectrosc Radiat Transfer 217, 53 (2018).

[4] N. C. Das, B. N. Rajasekhar, S. Padmanabhan, A. Shastri, S. N. Jha, S. S. Bhattacharya, S. Bhat, A. K.

Sinha, V. C. Saini, J Opt 32, 169 (2003).

[5] A. Kalinin, D. A. Banerji, P. R. Hannurkar, M. G. Karmarkar, S. Kotaiah, S. P. Mhaskar, P. K. Nema, S. S.

Prabhu, M. P. Kumar, S. Ramamurthi, Curr Sci 82, 283 (20022).

[6] M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert, M. S. Gordon, J. H. Jensen, S. Koseki, N.

Matsunaga, K. A. Nguyen, S. Su, T. L. Windus, M. Dupuis, J. A. Montgomery, J Comput Chem 14, 1347

(1993).


PP-05

Electron impact excitation of singly charged In and Sn ions

Swati Bharti*, Lalita Sharma and Rajesh Srivastava

Indian Institute of Technology Roorkee, Roorkee Uttarakhand, India 247667

*[email protected]

Studies on electron impact excitation of singly and multiply charged metal ions are important

for better understanding of atomic structure and have many practical applications in several

research areas including astrophysics, fusion research and material processing techniques. The

observations from Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space

Telescope (HST) indicate the existence of elements heavier than zinc in the interstellar medium

[1] including In II and Sn II. In II has been the subject of various experimental and theoretical

studies due to its significant presence in interstellar medium and application in solid state

lasers. It is also a good candidate for optical frequency precision. A detailed investigation of

absorption spectra of heavy elements relevant for astrophysical reasons and other plasma

applications shows that SnII has an abundance in interstellar medium [2].

A systematic study of the excitation process requires the knowledge of

accurate dipole transition probabilities or oscillator strength for spontaneous

emission between the various configurations of the ions. Therefore, it is very significant to

improve earlier calculations. A well optimized set of configuration state functions (CSFs) have

been considered for the atomic structure studies of these ions. Theoretical investigation using

the multiconfiguration Dirac-Fock (MCDF) method have been carried out for the 15 lines for

singly charged In ion and 10 fine structure transitions of Sn II, After ascertaining the quality

of the wave function, we carried out the electron impact excitation cross section calculations

using relativistic distorted wave theory. The excitation cross section for InII ion from ground

state configuration 5s2 1S0 to excited state configurations 5s5p and 5s6p and from excited state

configuration 5s5p to 5s6s and 5s5d, from 5s6s to 5s6p, from 5s5d to 5s6p excited state

configuration have been calculated within 20 to 200eV energy range of the incident electron

for 37 transitions. While for Sn II ion transitions from ground state 5s25p to excited state 5s25d,

5s5p2 and 5s26s have been investigated within same range of incident electron energy from 20

to 200eV. The fitted cross section parameters for desired purpose of plasma applications are

also listed for both of the ions considering further implementation.

References [1] J. A. Cardelli, Science 265 209 (1994)

[2] U. L. Sofia, D. M. Mayer and J. A. Cardelli, Astrophys. J, 522, L000 (1999)

https://www.sciencedirect.com/topics/engineering/dipole

https://www.sciencedirect.com/topics/chemistry/transition-probabilities

https://www.sciencedirect.com/topics/engineering/spontaneous-emission

https://www.sciencedirect.com/topics/engineering/spontaneous-emission


PP-06

Structural, vibrational and electronic spectroscopic study of

7-(4-trifluoromethyl) coumarin acrylamide using experimental and

theoretical methods 1D. Vijay, 2Asim Kumar Das, 2B. N. Rajasekhar and 1†A. Veeraiah

1Molecular Spectroscopy Laboratory, Department of Physics, D.N.R. College (A), Bhimavaram,

India-534202 2Atomic& Molecular Physics Division, BARC, Mumbai, India

†Corresponding author:[email protected]

Understanding photochemical behavior of structural isomers of 7-(4-trifluoromethyl)

coumarin acrylamide” (TFCA) having different properties of consequence in biological

activities demand spectroscopic information of this class of compounds. Barring 67-(4-

trifluoromethyl) coumarin acrylamide” (TFCA) other isomers of HC’s are well studied

spectroscopically. To understand and compare the photochemical activity of TFCA with other

isomers a detailed study of this molecule has been taken up. For this purpose, electronic,

vibrational and structural properties of TFCA have been studied using ultraviolet absorption

and Infrared spectroscopy techniques. Quantum chemical calculations have been performed at

DFT/B3LYP level of theory to get the optimized geometry and vibrational frequencies of

normal modes to support and analyze experimental data. The detailed vibrational assignments

were made on the basis of potential energy distributions. Chemical activity, molecular orbital

energies, band gap and hyper-polarizability information has been computed from quantum

chemical simulations. NBO analysis carried out helped in understanding the stability of the

molecule arising from hyper-conjugative interaction and charge delocalization. UV-Visible

spectrum of the compound recorded in the region 300-600nm helped in obtaining band gap

data of the compound. MolecularElectrostatic Potentials (MESP) plotted and the respective

centers of electrophilic -and nucleophililc attacks were predicted with the help of Fukui

functions calculations. Further, it was observed that the negative electrostatic potential regions

are mainly localized over the oxygen atoms and the positive regions are localized over the

benzene ring. Details of the results and analysis of experimental and theoretical spectroscopy

studies are presented in this paper.

Keywords: 7-(4-trifluoromethyl) coumarin acrylamide” (TFCA) , DFT, FT-IR, FT- Raman,

UV-Vis spectra and MESP,.

Keywords: 7-(4-trifluoromethyl) coumarin acrylamide (TFCA), DFT, FT-IR, UV-Vis Spectra

References:

[1] Marisa Spiniello, Anton Blencowe , Greg G. Qiao, J PolymSci Part A: PolymChem 46: 2422–2432, (2008)

[2] M K Subramanian, P M Anbarasan and S Manimegalai, journal of physics, Vol. 74, No. 5 pp. 845-860,

(2010)

[3] D. Vijay, Y. SushmaPriya, M. Satyavani, Asim Kumar Das, B.N. Rajasekhar, A. Veeraiah,

SpectrochimicaActa Part A: Molecular and Biomolecular Spectroscopy, S1386-1425(19)31321-6, (2019)



PP-07

Behavior of impurities in radiative improved mode plasmas

of ADITYA-U Tokamak

M. B. Chowdhuri1*, J. Ghosh1, R. Manchanda1, R. L. Tanna1, K. A. Jadeja1, N. Yadava2 , N.

Ramaiya1, S. Patel3, G. Shukla3 , K. Shah3, K. M. Patel1, Tanmay Makwan1 , U. C. Nagora1,

S. K. Pathak1, J. V. Raval1, M. K. Gupta1, M. V. Gopalakrishna1, K. Tahiliani1, Rohit

Kumar1, Suman Aich1, B. V. Nair1, C. N. Gupta1 and ADITYA-U Team1 1Institute for Plasma Research, Bhat, Gandhinagar 382 428, India

2The National Institute of Engineering, Mysuru 570 008, Karnataka, India 3Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382 007, Gujarat, India

*[email protected]

Impurity seeding in the tokamak plasma is done to obtain the improved confinement of the

plasma, which is known as radiative improved (RI) mode and considered as an alternative way

of operation for achieving fusion grade plasma. In this type of plasma operation, large fraction

(50 %) of input power goes to the radiation losses originating due to mid Z impurity seeding.

Not only that, impurity seeding into the tokamak plasma is used for the disruption mitigation

and also to reduce the heat load on the plasma facing components of the tokamak. In ADITYA-

U tokamak, experiments were carried out to obtain RI mode like plasma using neon and argon

gases puffing. It was found that line average electron density, ne and central electron

temperature, Te(0), were increased after the gas puffing. Substantial change in plasma edge

properties was observed with the increase of radiation loss and the reduction of hydrogen

recycling, which led to better plasma confinement. Here, the plasma effective charge, Zeff and

radiative loss play crucial role in to attaining the improved mode in impurity seeded plasma.

Then, the Zeff and radiative loss are studied with respect to various plasma parameters.

Impurities concentration of both intrinsic and those seeded into the plasmas are estimated and

their contributions into the radiation loss and Zeff are investigated. In this presentation, details

on the experiment and obtained results on impurity behavior will be discussed.


PP-08

Radial profile of visible continuum emission from ADITYA-U tokamak

plasmas

R. Manchanda1*, M. B. Chowdhuri1, J, Ghosh1, N. Yadava2 , N. Ramaiya1, S. Patel3, U. C.

Nagora1, S. K. Pathak1, J. V. Raval1, M. K. Gupta1, K. A. Jadeja, R. L. Tanna, C. N. Gupta

and ADITYA-U Team1 1Institute for Plasma Research, Bhat, Gandhinagar 382 428, India

2The National Institute of Engineering, Mysuru 570 008, Karnataka, India 3Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382 007, Gujarat, India

*[email protected]

The plasma effective charge, Zeff, is needed to be estimated to get an idea of the amount of the

impurity present in the tokamak plasma as the Zeff is one for pure hydrogen plasma and

increases with the presence of impurity. It is usually estimated through the measurement of

bremsstrahlung continuum emission around 536 nm in the visible wavelength range. For this

purpose, some spectroscopic diagnostics has been developed to measure the spatial profile of

visible continuum emission from ADITYA-U tokamak having plasma minor radius of 25 cm.

Here, the collimating beam probe having lens of focal length of 14 mm and diameter of 9 mm

is used to collect a, optical fiber with 1 mm diameter, 0.22 numerical aperture for transporting

and photo multiplier tube detecting the light from tokamak. A multi-channel wavelength

selection system based on multiple lenses, optical fiber and an interference filter having

diameter of 5 cm has been developed to select the required continuum emissions around 536

nm, which is spectral line free region, from many lines of sight passing through the plasma.

The spatial profile of emission has been collected through an indigenously developed double

O-rings based UHV compatible rectangular viewport covering the outer half of the plasma.

This diagnostic enables to measure the emission with a spatial resolution of 2.5 cm and total

eight chords have been employed to get the spatial profile. An Abel like matrix inversion

technique has been used to get centrally peaked radial profile of visible continuum emissions.

In this presentation, details on the diagnostics and initial result will be discussed.


PP-9

Calculations of total electron impact ionization cross sections for

Fluoroketone and Fluoronitrile

Nirav Thakkar1,*, Mohit Swadia2, Minaxi Vinodukmar3 and Chetan Limbachiya4

1 Sheth M. N. Science College, Patan-384 265 2 HVHP Institute of PG Studies and Research, Kadi-382 421

3V.P. & R.P.T.P. Science College, Vallabh Vidyanagar- 388 120 4Dept. of Applied Physics, The M S University of Baroda, Vadodara- 390 001

*[email protected]

We report theoretical results of electron driven processes for fluoroketone (C6F12O and

C5F10O) and fluoronitrile (C4F7N and C3F5N) molecules over a wide energy range from

ionization potential (IP) to 5000 eV. These gases are potential substitutes for SF6 molecules.

The electron impact ionization cross section (Qion) is the key parameter in the simulation of

gas discharges. Moreover, the Qion can be used in the preliminary screening of large scale

alternatives of SF6[1,2]. Recently, these molecules have also gained much attention because of

their low global warming potential (GWP). In industrial applications, while the gases

composed of C5F10O are used to generate gas discharge and low temperature plasmas, in all

such plasmas, ionization caused by the collision between electrons and fluoroketone and

fluoronitrile molecules is one of the fundamental processes. The electron-impact ionization

cross sections (Qion) are required to model the plasma processes and evaluate the insulating,

radiating, or cleaning performance of fluoroketone gases [2]. In order to describe the ionization

processes in various plasmas resulting from these gases, the electron-impact ionization cross

sections (Qion) of fluoroketone (C6F12O and C5F10O) and fluoronitrile (C4F7N and C3F5N) are

calculated by Complex Scattering Potential-ionisation contribution (CSP-ic) method [3,4].

Figure1. Qion for e- C5F10O scattering

We have shown in figure 1 the present Qion for e- C5F10O scattering compared with the data of

Zhong et al [2]. We have also calculated the total inelastic cross sections (Qinel) and summed

of total excitation cross sections (ΣQexc.) using the Spherical Complex Optical Potential

(SCOP) method [3]. We propose to present all the results in detail at the conference.

References [1] Wang, F et al., IEEE Transactions on Dielectrics and Electrical Insulation 26(5), 1693-1700 (2019).

[2] L.Zhong et al., 2018 Plasma Sources Sci. Technol. 27, 095005 (2018).

[3] Limbachiya et al., Mol. Phys. 113 (1), 55-62 (2015).

[4] Vinodkumar et al., Int. J. of Mass Spect. 339, 16-23 (2013).



PP-10

Ab initio study of structure, spectroscopic constants and thermal

properties of an ozone depleting reaction

Gargi Nandi* and T. K Ghosh

Department of Physics, Diamond Harbour Women’s University

Sarisha, South 24-Pgs, West Bengal-743368, India * [email protected]

Recently, there is a scientific and public interest grown up about the climatic change and there

by the environmental threat on the earth. The key factors responsible for this are the excessive

emission of Carbon Dioxide (CO2), Chloroflurocarbons (CFCs) and halogenated compounds,

which causes depletion of ozone layer in the atmosphere. The stratospheric ozone plays an

important role by absorbing most of the ultraviolet sunlight. Increasing concentrations of

hazardous chemicals, biomass burning, surface pollution and several other factors decrease the

ozone layer in stratosphere in different ways. So, it became an important tusk to find out a

complete phase out of these systems in ozone depletion. One of the ozone depleting reaction

is

X + O3 XO + O2 (X=Cl, Br, I).

However, experimental investigations are available for these systems, theoretical

investigations are limited in literature. In this report, ab initio calculations have been done to

investigate various minimum energy geometries and transition state geometries of this ozone

depleting reaction using an extensive correlation consistent basis set. Geometries and

frequencies have been identified at the MP2 level of theory. The energetics has been studied

at the Configuration Interaction level of theory. Several spectroscopic properties are calculated

and are compared with the available experimental data. IRC calculations are going on to find

the possible reaction pathway.



PP-11

Dissociation dynamics of multiply charged CO2 under impact of slow and

highly charged ions

S. Srivastav1*, D. Sharma1 and B. Bapat1 1Indian Institute of Science Education and Research, Homi Bhabha Road, Pune 411008

*[email protected]

When one or more electrons are removed from a neutral molecule, the molecular ion may

dissociate into its fragments. For the long time, CO2 molecule has been a simple and prototype

system to investigate the triple fragmentation [1-4]. Here, we are studying the triple

fragmentation of CO23+ ion under strong perturbation created by slow and highly charged ions

(HCI). Perturbation strength is parametrized by Sommerfeld parameter which is defined by the

ratio of projectile charge (q) and its velocity (v). Highly charged ions, Ar(1-16)+ with energy

from 5kev/q to 25kev/q, are obtained by newly installed electron beam ion source (EBIS) at

IISER Pune.

Depending on the states accessed by the molecule in perturabtion, molecular ion CO23+ follows

two types of dissociation pathways: ‘concerted’ and ‘sequential’. We separated and studied

these two breakup pathways with the help of Dalitz plot and Newton diagram [1]. We observed

the kinetic energy release (KER) distribution and trying to look at the effect of different

projectile charge and different velocity of projectile on KER. In HCI, capture is one of the

dominant ionization mechanism along with the direct ionization and in principle these two

mechanisms can be tuned by choosing projectile of suitable charge and velocity. We also have

designed cylindrical deflector post collision charge state analyzer to separate these two

ionization mechanisms to further investigate dissociation dynamics of multiply charged

molecular ions.

References

[1] Neumann N, Hant D, Schmidt L. Ph. H, Titze J, Jahnke T, Czasch A, Schoffler M. S., Kreidi K, Jagutzki O,

Schmidt-Bocking H, and Dorner R, Phys. Rev. Lett. 104, 103201 (2010).

[2] Khan A, Tribedi L. C, and Misra D, Phys. Rev. A 92, 030701(R) (2015).

[3] Yan S, Zhu X. L, Zhang P, Ma. X, Feng W. T, Gao Y, Xu, S, Zhao Q. S, Zhang S. F, Guo D. L, Zhao D. M,

Zhang R. T, Huang Z. K, Wang H. B, and Zhang X. J, Phys. Rev. A 94, 032708 (2016).

[4] Tezuka H, Takahashi K, Matsumoto J, Karimi R, Sanderson J H, and Shiromaru H, J. Phys. B 51, 035202

(2018).


PP-12

Electron beam ion trap/source for ion–molecule collisions in the non-

perturbative regime

B. Bapat1*, D. Sharma1 and S. Srivastav1

1 Indian Institute of Science Education and Research, Homi Bhabha Road, Pune 411008

*[email protected]

Among the variety of ion sources, the electron beam ion trap/source, which works on the

principle of magnetic compression of an intense electron beam, creating a significant space

charge potential and enhancing the rate of collisional ionisation, has the advantage of

producing ions with very high charge states at low energies [1]. Low energy, highly charged

projectiles are of great importance in exploring the response of molecules to slow, but heavy

perturbations. The typical ‘interaction time’ of a projectile with a molecule is taken to be a/v,

where a is the nominal size of the molecule and v is the projectile speed. When this time is

comparable to the vibrational time scales of molecules, we move significantly away from the

perturbative regime, requiring the use of non-perturbative quantum mechanical treatments to

predict the outcome of such collisions [2].

To investigate such collisions, one needs projectile energies of the order 10 keV/amu and

variable charge states. These are well provided by an ion source such as EBIS/T, with suitable

acceleration. The source at IISER Pune is based on a thermionic electron emitter and

permanent magnets for compression of the electron beam [3]. The complete source is raised to

a positive potential between 10–30 keV, allowing the extraction of 10–30 keV/q beams. Charge

states upto Ar 16+ can be produced and extracted. The distribution of charge states in the

source/trap can be controlled by changing the conditions in the trap, viz. the electron flux,

electron energy, trapping time and pressure. The trap can be operated in the pulsed mode or a

continuous,‘leaky’ mode. A Wien Filter with an aperture of 1.0 mm is employed to separate

the charge states before the ions enter the beam line. The beamline consists of an einzel lens

and an electrostatic quadrupole deflector, which couples downstream to the collision chamber.

The ion beam crosses an effusive gas jet in the collision chamber. Analysis of the collision

fragments is done by a multi-coincidence of an ion momentum spectrometer. Projectile ions

that have undergone charge change in the collision are separated by a cylindrical sector charge

state analyser. This will be a user facility soon.

References

[1] Donets E D , Rev. Sci. Instrum. 69, 614 (1998).

[2] Lüdde H J, Spranger T, Horbatsch M and Kirchner T , Phys. Rev. A 80, 060702R (2009).

[3] Schmidt M, Zschornack G, Kentsch U and Ritter E, Rev. Scient. Instr. 85 ,02B704 (2014).


PP-13

Orientation effect in multiple ionisation of OCS under proton and C2+

impact at 50 keV

D. Sharma1*, B. Bapat1, P. Bhatt2 and C. P. Safvan2 1 Indian Institute of Science Education and Research Pune, Homi Bhabha Road, Pune 411008

2 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067

*[email protected]

Under the impact of charged particles, one or multiple electrons can be removed from the target

molecule. Depending on the electronic state of transient molecular ion, it can be stable or

dissociate into it’s fragments. Dissociation of multiply ionised triatomic or large molecules can

proceed via concerted (all the bonds break simultaneously) or sequential (step wise process)

pathways. The method of Newton diagram and Dalitz plot have been widely used [1,2] to

separate the dissociation channels. Recently, a new representation based on angular correlation

of fragments has been used by Rajput et al [3].

Furthermore, the electronic cloud of a molecule is not spherical symmetric. Therefore, in ion-

molecule collisions, the multiple ionisation is expected to depend on the orientation of the

molecule with respect to incident projectile. In recent papers [4,5], we have discussed the

angular distribution of fragments from dissociation of multiply ionised CO molecule. Together

with anisotropy, asymmetry in the distribution was observed, owing to the heteronuclear nature

of CO molecule. Furthermore, it was shown that orientation effect is a function of interaction

strength of the projectile which is parameterized by Sommerfeld parameter k = q/v, where q

and v are the charge and velocity of projectile in atomic units. When a diatomic molecular ion

is formed in a dissociative state, the dissociation products move apart along the straight line

defined by the internuclear axis of the molecule. The orientation of the molecule can be

determined from momentum vectors of fragment ion. The case is simple for two body

dissociation of triatomic molecule, but for three body breakup, the measurement of this angle

is difficult because of the mixing of sequential and concerted channels. Even for a pure

concerted channel, the asymptote angle between the fragments is different from the actual bond

angle of the molecule because of mutual repulsion of the fragments ions.

Here, we present an experimental study of dissociation dynamics of OCS molecule under

proton and C2+ impact at 50 keV such that the interaction strength is 0.70 (k < 1) for proton

and 4.86 (k >1) for C2+. The experiment was performed at low energy ion beam facility

(LEIBF) at Inter University Accelerator Center, New Delhi. For a particular dissociation

channel, angular distribution of the fragments and kinetic energy release has been measured.

Strong orientation effect is observed under proton impact as compare to C2+ impact.

Experimental results are further compared with the case of diatomic molecules and earlier

studies of triatomic molecules.

References

[1] Neumann N, Hant D, Schmidt L P H, Titze J, Jahnke T, Czasch A, Schöffler M S, Kreidi K, Jagutzki O,

Schmidt-Böcking H and Dörner R, Phys. Rev. Lett. 104(10), 103201 (2010).

[2] Khan A, Tribedi L C and Misra D, Phys. Rev. A 96(1), 012703 (2017).

[3] Rajput J, Severt T, Berry B, Jochim B, Feizollah P, Kaderiya B, Zohrabi M, Ablikim U, Ziaee F,Raju P K,

Rolles D, Rudenko A, Carnes K D, Esry B D and Ben-Itzhak I, Phys. Rev. Lett. 120(10), 103001 (2018).

[4] Sharma D, Bapat B, Bhatt P and Safvan C P, Journal of Physics B: Atomic, Molecular and Optical Physics

51, 195202 (2018).

[5] Sharma D, Bapat B, Bhatt P and Safvan C P, Journal of Physics B: Atomic, Molecular and Optical Physics

52, 115201 (2019).


PP-14

Electron interaction with Para-Benzoquinone(C6H4O2) and

Naphthoquinone(C10H6O2)

Dhaval Chauhan1* and Chetan Limbachiya1

1 The M.S. University of Baroda, Vadodara – 390001

*[email protected]

We report theoretical results of electron driven processes for Para-Benzoquinone(C6H4O2) and

Naphthoquinone(C10H6O2) molecules over a wide energy range from ionization potential

(IP) to 5000 eV.

Quinone and its derivatives such as Para-Benzoquinone(C6H4O2) and Naphthoquinone

(C10H6O2) play a vital role in numerous electrochemical reactions for energy transduction and

storage, such processes include respiration and photosynthesis [1]. For example, fast proton-

coupled electron transfer between primary and secondary quinones in green plants triggers the

rapid charge separation of chlorophyll molecules, achieving unparalleled photosynthesis with

near-unity quantum yield. In addition, quinone-rich polymers such as eumelanin and

polydopamine show unique optical and electrical properties (e.g., strong broadband

absorbance or a switching response to external stimuli), mostly arising from their chemically

disordered structures [2]. Understanding the unique features of quinone and its derivatives can

provide solutions to the construction of bio-inspired systems for energy harvesting and

conversion [3,4]. Applications of this, in energy-harvesting and storage systems, such as

artificial photosynthetic platforms, rechargeable batteries, pseudo-capacitors, phototransistors,

plasmonic light harvesting platforms, and dye-sensitized solar cells [4,5].

The present study is aimed to provide reliable elastic, inelastic and ionization cross sections

data for electron scattering from para-benzoquinone and Naphthoquinone which are used in

many electrical and optical properties. So, we employ Spherical Complex Optical Potential

(SCOP) and Complex Scattering Potential – ionization contribution (CSP-ic) methods to study

the electron induced processes [6].

References: [1] D.B. Jones et al, The J. Chem. Phys. 148, 204305 (2018).

[2] D.B. Jones et al, The J. Chem. Phys. 145, 164306 (2016).

[3] B. Huskinson, M. P. Marshak, C. Suh, S. Er, M. R. Gerhardt, C. J. Galvin, X. Chen, A. Aspuru-Guzik, R.

G. Gordon and M. J. Aziz, Nature 505, 195 (2014).

[4] Y. Ding and G. Yu, Angew. Chem., Int. Ed. 55, 4772 (2016).

[5] E. Son, J, Kim, K. Kima and C.Park, J. Mater. Chem. A 4,11179 (2016).

[6] Yogesh Thakar et. al, Planetary and Space science 168,95-103 (2019).



PP-15

Electron impact elastic scattering cross section from acetylene

Dibyendu Mahato1*, Lalita Sharma1 and Rajesh Srivastava1

1 Department of physics, IIT Roorkee, Uttarakhand, INDIA

*[email protected]

Electron scattering elastic cross section data from small hydrocarbon molecule, Acetylene

(C2H2) is very important to understand the plasma and modeling plasma. Also C2H2 is an

important molecule in astrophysics environment. There are few measurements and

theoretical calculations have been reported with different techniques. We have obtained our

e-C2H2 cross section calculation by using an analytic expression of static potential using the

STO-6G Gaussian wave function. We have evaluated the interaction of C-H or H-H by

solving the Gaussian integration through Euler angle rotation for a fixed molecular frame. A

non-relativistic Schrödinger equation has been solved to obtained the e-C2H2 scattering cross

sections. Our DCS results for acetylene are shown in figure 1 and compared with the

available theoretical and experimental results [1,2]. Our results show excellent agreement

with previous experiments and theory.

Figure 1. Electron impact differential cross section from Acetylene for incident electron

energies 80eV (a) and 150 eV(b)

Reference

[1] Song M Y, Yoon J S, Cho H, Karwasz G P, Kokoouline V, Nakamura Y and Tennyson J, J. Phys. Chem.

Ref. Data 46.1, 013106 (2017)

[2] Iga I, Lee M T, Rawat P, Brescansin L M and Machado L E, Eur. Phys. J. D 31, 45 (2004)


PP-16

Electron impact excitation cross-sections of magnesium for plasma

applications

S S Baghel1*, S Gupta1, R K Gangwar2 and R Srivastava1

1 Indian Institute of Technology Roorkee 2 Indian institute of Technology Tirupati

*[email protected]

Electron impact excitation cross-sections has significant application in plasma modelling [1].

In the present work, we calculate the electron impact excitation cross-section of Magnesium

for Plasma applications from its ground state into 34 different energy levels corresponding to

configuration 3s3p, 3s4s, 3s3d, 3s4p, 3s5s, 3s4d, 3s5p, 3s6s, 3s5d, 3s6p and also from levels

of configuration 3s3p into 3s4s, 3s5s, 3s6s, 3s3d, 3s4d, 3s5d for electron energy from threshold

to 500 eV. We use Relativistic distorted wave (RDW) theory for calculation of cross-

sections[2]. The ground and excited states of magnesium is represented through Multi

Configuration Dirac-Fock (MCDF) wave functions and obtained through GRASP2K code[3].

The calculated oscillator strength for various allowed transitions of Magnesium from its

ground as well as excited states is also compared of Magnesium to that of NIST[4].

References [1] Boffard J B, Lin C C and DeJoseph C A, J. Phys. D. Appl. Phys., 37 R143 (2004)

[2] Baghel S S, Gupta S, Gangwar R K and Srivastava R, Plasma Sources Sci. Technol., 28 115010 (2019)

[3] Jönsson P, He X, Froese Fischer C and Grant I P, Comput. Phys. Commun., 177 597 (2007)

[4] Kramida A ., Ralchenko Y, Reader J and Team N A (2018) NIST: Atomic Spectra Database ( version 5.6.1)

NIST At. Spectra Database (ver. 5.6.1), [Online]. Available https//physics.nist.gov/asd [2019, Dec 20]. Natl.

Inst. Stand. Technol. Gaithersburg, MD.


PP-17

Study of the nature of impurity transport coefficients using separate

atomic databases in the ADITYA tokamak

A. Bhattacharya1,*, J. Ghosh2, M. B. Chowdhuri2, P. Munshi1 and the ADITYA team2

1 Indian Institute of Technology Kanpur, Kalyanpur, Kanpur–208016, Uttar Pradesh, India 2Institute for Plasma Research, Gandhinagar, Bhat–382428, Gujarat, India

*[email protected]

Analysis of impurity transport in the tokamak plasma and their contributing factors, through

experiments and modeling, has been an important topic of tokamak research for more than a

decade [1, 2]. Impurity elements are the non–fuel species in tokamak plasma that are mainly

generated towards the plasma boundary, near the wall and limiters/divertors of the system,

which gradually enter into the main plasma and can lead to either radiation losses or plasma

dilution disrupting the tokamak operations. Temporal evolutions and radial distributions of the

impurity ions in tokamak are numerically obtained by solving the radial impurity transport

equation [3]. The radial impurity transport equation for tokamak plasma is a set of non–linear,

parabolic, diffusion–convection–reaction equation, coupled through its source (reaction) term

and the distributions of all ionization states of an impurity element are simultaneously obtained

numerically. A novel approach of numerically solving the radial impurity transport equation

with a semi–implicit method has recently been discussed in literatures [4, 5] and will be

featured in this presentation. The presentation will further show the comparison between the

experimental [6] and simulated radial emissivity profiles of the 650.024 nm (2p3p3D3–2p3d3F4)

O4+ (visible) spectral line for both (inboard/outboard) regions of the ADITYA tokamak (ro=

0.25 m, R= 0.75 m, Bt,o= 0.75 T), installed at the Institute for Plasma Research (IPR)

Gandhinagar, India. The simulated radial (inboard/outboard) emissivity profiles of the O4+

transition have been determined using the (inboard/outboard) O4+ number densities obtained

from the semi–implicit form of the radial impurity transport equation and the 650.024 nm

Photon Emissivity Coefficient (PEC) data from two separate databases namely the Atomic

Data and Analysis Structure (ADAS) database and the National Institute for Fusion Science

(NIFS) database, Japan. The (inboard/outboard) impurity diffusion coefficient, although an

input to the linearized numerical form of the radial impurity transport equation, is also the

outcome of the study and is decided based on the simulated emissivity profiles which best

represents (‘best–fit’) the experimentally obtained (650.024 nm) emissivity data. A difference

in the natures of the radial impurity diffusivity profiles, corresponding to the best–fit simulated

emissivity profiles, is observed when the two separate aforementioned PEC databases are used

[5, 7]. The difference in the radial (inboard/outboard) emissivity profile and thereby the

(inboard/outboard) impurity diffusivity profile occurs due to the differences in the atomic

processes (transitions) considered while calculating the excitation rate coefficients in the two

databases (ADAS and NIFS) [7] and will be addressed in the presentation. Analytical (model–

based) calculations featured in the presentation will further validate the factors contributing to

the anomalous nature of impurity diffusivity conjectured by the simulation profiles

corresponding to the two (ADAS and NIFS) databases.

References [1] C. Angioni et al., Physics of Plasmas 14, 055905 (2007)

[2] B. A. Grierson et al., Physics of Plasmas 22, 055901 (2015)

[3] R. Dux, and A. G. Peeters, Nuclear Fusion 40 (10), 1721–1729 (2000)

[4] A. Bhattacharya, P. Munshi, J. Ghosh, M. B. Chowdhuri, Journal of Fusion Energy 37 (5), 211–237 (2018)

[5] A. Bhattacharya, J. Ghosh, M. B. Chowdhuri, P. Munshi, I. Murakami, and the Aditya team, Plasma and

Fusion Research 14, 1403155 (2019)


PP-18

C-R model for Ar-CO2 mixture plasma using reliable fine structure

cross sections

Neelam Shukla1, Reetesh Gangwar2 and Rajesh Srivastava1

1Department of Physics, Indian Institute of Technology Roorkee, Roorkee-247667, India 2Department of Physics, Indian Institute of Technology Tirupati, Tirupati-517506, India

The carbon dioxide (CO2) gas plasma are very interesting due to its application in numerous

fields such as plasma polymerization, etching, deposition, etc. In order to achieve efficient

processing in a specific application, it is important to understand the discharge-kinetics by

employing the appropriate diagnostic approach. The inert gas optical emission spectroscopy

approach is very suitable for diagnostic of these plasmas. It can provide information about

electron temperature and density which are key parameters to monitor in any plasma mediated

processing. In this light the Ar is the most preferred choice due to its relatively lower cost.

Moreover the addition of Ar gas in CO2 plasmas also assist in maintaining the discharge at

relatively lower power. It is mainly due to the fact that the ionization energy of Ar is lower

than the CO2 molecules.

However, in order to extract plasma parameters, the OES measurements need to be coupled

with a suitable collisional radiative (CR) model. Using our calculated relativistic cross-

sections, we developed a fine structure resolved CR model for Ar atom. In the present study,

we applied our CR model to study the discharge-kinetics of Ar/CO2 mixture plasma. The OES

measurements are taken from a recent study reported by Martinez et al. [1]. They reported the

OES measurements of Ar/CO2 (20-80%) gas mixture plasma. In the present work, we have

modified our pure Ar inert gas CR model and applied it to study the measurements reported

by Martinez et al. [1]. Previously, we have also extended our model to other inert gas mixture

plasmas [2, 3]. The further modeling results along with discussion shall be presented during

the conference.

References [1] Martinez et. al., J. Phys. D: Appl. Phys. 47, 335206 (2014)

[2] Shivam et al., Spectrochimica Acta part B, 149 203-213 (2018)

[3] Priti et al., J. Quant. Spectrosc. Radiat. Transfer 187, 426 (2017)


PP-19

Modeling the tunneling reaction 𝑵𝑯𝟐+ + 𝑯𝟐 → 𝑵𝑯𝟑

+ + 𝑯 at interstellar

temperature by variational transition state theory

M. Salvi1*, Raghunath O. Ramabhadran2 and S. Sunil Kumar1

1Department of Physics, IISER Tirupati, Tirupati-517507, Andhra Pradesh, India 2Department of Chemistry, IISER Tirupati, Tirupati-517507, Andhra Pradesh, India

*[email protected]

Nitrogen-containing molecules form a class of the key species in the chemistry of the

interstellar medium [1]. The reaction of interest, 𝑁𝐻2+ + 𝐻2 → 𝑁𝐻3

+ + 𝐻, is an important step

in the pathway of gas-phase formation of ammonia by hydrogen abstraction. The current study

contributes to a better understanding of nitrogen chemistry in the interstellar medium. The rate

coefficient for this gas-phase reaction is addressed by using variational transition state theory

(VTST). Møller-Plesset (MP2 & MP2(full)) and coupled cluster single double (CCSD &

CCSD(full)) levels of theory have been employed for the calculation. The study demonstrates

the necessity of incorporating quantum effects such as tunneling and zero-point energy for

modeling the reaction 𝑁𝐻2+ + 𝐻2 → 𝑁𝐻3

+ + 𝐻.

Figure 1. Relative energy diagram of species involved in the reaction calculated in MP2/aug-

cc-pVTZ level of theory.

The computed rate coefficient monotonically decreased from 𝑘𝑁𝐻2+(25 K) = 1.05 ×

10−9 cm3mol−1s−1 to 𝑘𝑁𝐻2+(298 K) = 1.26 × 10−9 cm3mol−1s−1 as temperature is

increased. Comparison of the calculated rate coefficient with the experimentally determined

values [2] confirms that the reaction proceeds by tunneling through a potential barrier.

References [1] Eric Herbst, D J DeFrees, and A D McLean, ApJ 321, 898-906 (1987).

[2] S Rednyk, Š Roučka, A Kovalenko, T D Tran, P Dohnal, R Plašil, and J Glosík, A&A 625, A74 (2019).



PP-20

Electron scattering from HCNO

Paresh Modak1, Nafees Uddin1,*, and Bobby Antony1

1Indian Institute of Technology (Indian School of Mines) Dhanbad *[email protected]

HNCO is a very interesting target since it contains the four basic life-forming chemical

elements. As such, it has been attracting attention as a possible prebiotic precursor [1] in

formation of the peptide bond. Its presence has been confirmed in a number of interstellar

environments: interstellar clouds [2], young stellar objects [3], molecular outflows [4], and

comets [5]. In the interstellar space, the ultraviolet light, x-rays, and cosmic rays interact with

interstellar icy grains that serve as reservoirs for chemical species, and an avalanche of

secondary electrons is produced. Therefore, the electron-induced processes of this molecule is

of high astrophysical interest. In the present study, we made direct investigation of elastic and

inelastic processes for e-HCNO scattering employing UK R-matrix [6] formalism.

References [1] L. Song and J. Kastner, Phys. Chem. Chem. Phys. 18, 29278 (2016)

[2] B. E. Turner, R. Terzieva, and E. Herbst, Astrophys. J. 518, 699 (1999).

[3] S. E. Bisschop, J. K. Jorgensen, E. F. van Dishoeck, and E. B. M. de Wachter, Astron. Astrophys 465,

913 (2007)

[4] N. J. Rodriguez-Fernandez, M. Tafalla, F. Gueth, and R. Bachiller, Astron. Astrophys 516, A98 (2010).

[5] D. C. Lis, J. Keene, K. Young, et al., Icarus 130, 355 (1997).

[6] L.A.Morgan, J.Tennyson, and C.J.Gillan,Comput. Phys. Commun. 114, 120-128 (1998)


PP-21

Pulse width effect on the ionization and dissociation of

methyl iodide in the intense femtosecond laser field

Arnab Sen1*, Bhas Bapat1, Ram Gopal2 and Vandana Sharma3 1Indian Institute of Science Education and Research, Pune 411008, India

2Tata Institute of Fundamental Research, Hyderabad 500107, India 3Indian Institute of Technology Hyderabad, Kandi 502285, India

*[email protected]

The ionization rate of the diatomic molecule in an intense laser field has been observed to be

enhanced for inter-nuclear separation greater than it’s equilibrium bond length ’RE’. This

specific inter-nuclear separation is known as ’critical’ bond length ’Rc’, where the HOMO

(Highest occupied molecular orbital) and LUMO (Lowest unoccupied molecular orbital) starts

to overlap in the presence of the laser field [1]. Previous results on diatomic molecules showed

that the typical ’Rc’ could be two to three times greater than the ’RE’. Several experiments

have been performed on diatomic molecules to understand the ionization mechanism and the

dissociation dynamics by changing various parameters such as intensity, pulse width of the

laser field. It has been observed that enhanced ionization dominates for larger pulse duration

(~ 100fs) and suppressed for few-cycle pulses (~ 10fs), as the molecular ion does not have

sufficient time to reach ’Rc’ within the duration of the pulse. To follow the appearance of the

enhanced ionization and investigate its molecular origin, it would be better to vary the pulse

duration from few-cycle to multi-cycle regime. Few experiments of this kind have been done

for diatomic molecules and small polyatomic molecules having simple geometry, such as CO2

[1], which has a linear molecular geometry. For polyatomic molecules with critical geometry

the ionization mechanism and dissociation pathways remain matter of interest. Here in this

work we have irradiated intense (~ 1012 W/cm2) laser pulse of 800nm on CH3I molecule,

which has a tetrahedral geometry. We have varied the pulse width from 25fs to 1200fs to

understand the ionization mechanism and the dissociation pathways in a systematic manner.

Being a large molecule the vibrational time period of the C-I bond is quite large(~100fs), so

we can easily consider the C-I bond to be frozen for the pulse duration of 25fs. We have used

velocity map imaging techniques [3] to collect all the fragmented ions. Here we have closely

looked into the fragments originating from the ’Coulomb Explosion’ pathways, such as from

CH3I++ → CH3+ + I+ and CH3I+++ → CH3

+ + I++. Coulomb explosion in molecules is extensively

studied to understand different dissociation pathways and to reconstruct the molecular structure

at the moment of the explosion. The measured kinetic energy of the fragmented ions

originating from Coulomb explosion processes has been observed to decrease with increasing

pulse duration, which is a clear indication of increasing bond length. Molecules in laser field

undergo rotation and align itself along the laser polarization axis, it is known as dynamical

alignment. The observed angular distribution of the fragmented ions confirms the ’dynamical

alignment’ and with increasing pulse width molecules become more aligned. Interestingly, we

have also seen C+, CH+ and CH2+ fragments in coincidence with I+ and I++, and the yield of C+,

CH+ and CH2+ fragments increase with increasing pulse duration. From the kinetic energy

distribution of these fragments we can confirm they are coming from further dissociation of

CH3+. The possible reason for increasing further dissociation of CH3

+ fragment could be due

to the increasing geometric distortion on the molecular ion as it gets aligned with increasing

pulse width.

References [1] Bocharova. Irina, Karimi. Reza, Penka. Emmanuel F.,Brichta. Jean-Paul, Lassonde. Philippe, Fu. Xiquan,

Kieffer. Jean-Claude and Bandrauk, André D. and Litvinyuk. Igor, Sanderson, Joseph, Légaré,

François, Phys. Rev. Lett. 107, 063201 (2011).

[2] Zuo, T. and Bandrauk, A. D., Phys. Rev. A 52, R2511 (1995).

[3] Gopal,R. and Sen,A. and Sahu,S. R. and Venkatachalam,A. S. and Anand,M. and Sharma,V., Review

of Scientific Instruments 89, 086107(2018)


PP-22

Double slit projectile wave interference at slow and intermediate

electron transfer collisions

Md A. K. Azad Siddiki1, Nrisimhamurty Madugula2, M.A. Rehman1, M.R. Chowdhury1,

L.C. Tribedi1 and Deepankar Misra1*

1Tata Institute of Fundamental Research, Mumbai-400005, India 2 University of Florida, FL 32611, USA

*[email protected]

We have performed a series of electron capture experiments for various low projectile

velocities (vp) ranging between 0.35 a.u. and 1 a.u. with diatomic molecules like H2, N2 and

O2, using COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) [1]. The

measurements are carried out at the Electron Cyclotron Resonance Ion Accelerator (ECRIA)

facility [2], TIFR. The prime focus of these experiments is to investigate the fundamental

concept of wave-particle duality at high perturbation regime. The very small de Broglie

wavelength (λdB ~ 10 fm) corresponding to incoming projectile wave scatters on both the

centres of the target molecules. During capture there is a change in de Broglie wavelength

which manifests the interference effect. The molecular dissociation happens in tens of

femtoseconds compare to molecular rotation which is in picoseconds. Therefore, the axial

recoil approximation is valid during dissociation. The quantum mechanical interference effects

are manifested, in the present experiment, as the variations of transfer excitation cross sections

with respect to the molecular orientations. This can be modelled as follows [3, 4]:

,

where A and V are free parameters. Here, δϕ is the phase shift between two projectiles de

Broglie waves which interact with both the molecular centres. Details of the measurements

will be presented.

References [1] Arnab Khan et al, RSI 86(4):043105 (2015).

[2] A. N. Agnihotri et al, Phys. Scr. T 144, 014038 (2011).

[3] H. T. Schmidt et al, PRL 101, 083201 (2008).

[4] D. Misra et al, PRL 102, 153201 (2009).


PP-23

Mercury hydroxide as a promising triatomic molecule to probe P, T-odd

interactions

R. Mitra1,2, V. S. Prasannaa1* and B. K. Sahoo1, X. Tong2, M. Abe3 and B. P. Das4

1 Atomic, Molecular, and Optical Physics Division, Physical Research Laboratory, Navrangpura,

Ahmedabad-380009, India 2 Indian Institute of Technology Ganhinagar, Palaj, Gandhinagar-382355, India

3Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan-430071, China 4Department of Chemistry, Tokyo Metropolitan University, Tokyo-1930397, Japan

5Department of Physics, Tokyo Institute of Technology, Tokyo-1528550, Japan

*[email protected]

In the quest to find a favourable triatomic molecule for detecting the parity- and time-reversal

violating electric dipole moment of an electron (eEDM), we identify mercury hydroxide

(HgOH) as an extremely attractive candidate from both experimental and theoretical

viewpoints. Our calculations show that there is a four-fold enhancement in the effective electric

field of HgOH as compared to the recently proposed ytterbium hydroxide (YbOH) [1] for

eEDM measurement. Thus, in the (010) bending state associated with the electronic ground

state, it could provide better sensitivity than YbOH from a theoretical point of view. We have

also investigated the potential energy curve and permanent electric dipole moment of HgOH,

which lends support for its experimental feasibility. Moreover, we propose that it is possible

to laser cool the HgOH molecule by adopting the same technique as that in the diatomic polar

molecule, HgF, as shown in [2].

References [1] I. Kozyryev, and N. R. Hutzler, Phys. Rev. Lett. 119, 133002 (2017). [2] Z. Yang, J. Li, Q. Lin, L. Xu, H. Wang, T. Yang, and J. Yin, Phys. Rev. A 99, 032502 (2019).


PP-24

Electron interaction with Fluorocompounds for application in plasma

sciences

Smruti Parikh1* and Chetan Limbachiya1 1 The M.S. University of Baroda, Vadodara-390 001

*[email protected]

Studies on collisions of electrons with various radicals and molecules have remained an

important subject of interest since long. Interest in these collisions arises in view of the

applications of relevant cross-section data in various pure and applied sciences [1,2]. Electron

induced ionization and other processes determine the density and reactivity of low-temperature

technological plasmas. In general the electron induced processes, including ionization as a

dominant inelastic channel at intermediate and high energies, play important roles in plasma

processing, aeronomy and in biological systems. Electron-impact cross sections for molecular

targets, including their radicals, are important in developing plasma reactors and testing

various plasma processing gases [3]. The aim of this effort is to build the quantitative analysis

for electron interaction processes with molecules relevant to plasma processing, such as CFx

(x=1 to 4), C2F4, C3F8, C3F6, C6F6, etc.

We report study on various total cross-sections for collisions of electrons in the energy from

threshold to 5000 eV for these plasma molecules. Spherical complex optical potential (SCOP)

formalism [4] is employed to evaluate total elastic cross-section,Qel and total cross-section, QT.

Total ionization cross sections, Qion, are derived from total inelastic cross sections, Qinel, using

our complex spherical potential – ionization contribution (CSP-ic) method [5].

References

[1] N.J. Mason, J.M. Gingell, N.C. Jones, L. Kaminski, Phil. Trans. R. Soc. Lond. A 357, 1175 (1999).

[2] H. Deutsch, K. Becker, S. Matt, T.D. Maerk, Int. J. Mass Spectrom, 197, 37 (2000), and references therein.

[3] J. -S. Yoon, M. J. Brunger et. al., Journal of Physical and Chemical Reference Data 39, 033106 (2010).

[4] Yogesh Thakkar et. al., Planetary and Space science 168,95-103(2019).

[5] K. N. Joshipura and N. J. Mason, Cambridge University Press, (2019).


PP-25

A comparative analysis of non-relativistic and relativistic calculations of

electric dipole moments and polarizabilities of heteronuclear alkali dimers

R. Mitra1,2, V. S. Prasannaa1* and B. K. Sahoo1 1 Physical Research Laboratory, Atomic, Molecular and Optical Physics Division, Navrangpura,

Ahmedabad-380009, India 2 Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar-382355, Gujarat, India

*[email protected]

We analyze the molecular electric dipole moments (PDMs) and static electric dipole

polarizabilities of heteronuclear alkali dimers in their ground states by employing coupled-

cluster theory, both in the non-relativistic and four-component relativistic frameworks. The

roles of electron correlations as well as relativistic effects are demonstrated by studying them

at different levels of theory, followed by a comprehensive treatment of error estimates. We

compare our obtained values with the previous non-relativistic calculations, some of which

include lower-order relativistic corrections, as well as with the experimental values, wherever

available. We find that the PDMs are sensitive to relativistic effects, as compared to

polarizabilities. We show that consideration of relativistic values of PDMs improves

significantly the isotropic Van der Waals C6 coefficients of the investigated alkali dimers over

the previously reported non-relativistic calculations. The dependence of dipole

polarizabilites on molecular volume is also illustrated.


PP-26

Characterizing Laguerre-Gaussian pulses using angle-resolved attosecond

streaking

Irfana N. Ansari1*, Deependra S. Jadoun1 and Gopal Dixit1*

1 Department of Physics, Indian Institute of Technology Bombay, Mumbai, India

* [email protected], [email protected]

Light can carry orbital angular momentum, along with the spin angular momentum, due to

their spatial structure. The presence of this extra angular momentum has been exploited

extensively such as for nanoparticle trapping, quantum state engineering in Bose-Einstein

condensates, and chiral recognition in molecules. Here, we have proposed a method to directly

characterize the orbital angular momentum of the Laguerre-Gaussian (LG) pulse. The

technique, called as attosecond streaking, involves photo-emission of an electron from the

hydrogen atom by XUV- LG pulse, which are then deflected in angular spatial directions by

circularly polarized IR pulse. We have shown that the units of orbital angular momentum

present in LG pulse is directly reflected in the angle-resolved streaking spectra.



PP-27

Theoretical investigation of various inelastic processes of e-CO2 scattering

S. Vadhel1, M. Vinodkumar2 and P. C. Vinodkumar1

1 Department of Physics, Sardar Patel University, Vallabh Vidyanagar, Gujarat, India 2 V. P. & R. P. T. P. Science College, Vallabh Vidyanagar, Gujarat, India

*[email protected]

Carbon dioxide (CO2) is vital component of planetary atmosphere and is found in abundance

particularly in the atmosphere of Venus and Mars. On the contrary, even though the

concentration of CO2 in earth’s atmosphere is small, it is the most noteworthy greenhouse gas

on Earth’s atmosphere. Electron impact scattering study of CO2 is widely used in gaseous

discharges or low-temperature plasma devices and in CO2 laser etc. Because of its importance

it has been studied both theoretically [1] as well as experimentally [2].

In the present work, we compute electron impact collision cross sections for e-CO2 scattering

over a wide range of impact energies starting from 0.01 eV to 5000 eV. Such a wide energy

range encompasses many interaction phenomenon which are predicted in terms of quantitative

cross sections. Since a single theoretical formalism is insufficient for modelling all these

phenomenon, we have used unification of two theoretical methods viz. R-matrix [3] and

spherical complex optical potential (SCOP) methods [4, 5]. The detailed results will be

presented in the conference.

Acknowledgement: Mr. Sagar Vadhel and Dr. Minaxi Vinodkumar acknowledges DST-SERB, New

Delhi for major research project [EMR/2016/000470] for financial support under which part of this

work is carried out.

References [1] Yukikazu Itikawa, J. Phys. Chem. Ref. Data 31, 749 (2002)

[2] Czeslaw Szmytkowski, Antonio Zecca, Grzegorz Karwasz, Stefan Oss, Krzysztof Maciggt, Bratislav

MarinkoviC, Roberto S Brusa and Rolly Grisenti, J. Phys. B: At. Mol. Phys. 20, 5817-5825 (1987)

[3] J. Tennyson, Phys. Rep. 491, 29 (2010)

[4] M. Vinodkumar, H. Desai, P. Vinodkumar. RSC Adv 5(31), 24564 (2015)

[5] Minaxi Vinodkumar, Chetan Limbachiya, Hardik Desai and P. C. Vinodkumar, Phys. Rev A 89, 062715

(2014)


PP-28

Relativistic coupled-cluster calculations of electric dipole polarizability of

Al and In

Ravi Kumar1 and B. K. Mani1

1 Department of Physics, Indian Institute of Technology Delhi, Hauz Khas, New Delhi, India.

[email protected]

High precision calculation of electric dipole polarizability, α, plays important role in the study

of optical properties of materials, atom-electron scattering, interatomic potential, collision

induced spectral shifts, atomic clocks, and discrete symmetry violations [1-5]. Accurate

theoretical data of α for open-shell atomic systems is rare due to complicated electron

correlations and relativistic effects. In this context, we have developed methods based on

perturbed relativistic coupled-cluster (PRCC) theory for the properties calculation of one-

valence atoms or ions which accounts for electron correlation effects to all orders in

perturbation. In this work, we employ this method to calculate α for the ground states (p1/2 and

p3/2) of Al and In atoms. Results from this study will be useful in developing the new frequency

standards and will also provide important inputs to discrete symmetry violating atomic

experiments.

References

[1] T. M. Miller and B. Bederson, Adv. At. Mol. Phys. 13, 1 (1977).

[2] T. M. Miller and B. Bederson, Adv. At. Mol. Phys. 25, 37 (1988)

[3] D. P. Shelton and J. E. Rice, Chem. Rev. (Washington, D.C.) 94, 3 (1994).

[4] K. D. Bonin and V. V. Kresin, Electric-Dipole Polarizabilities of Atoms, Molecules and Clusters (World

Scientific, Singapore, 1977).

[5] M. S. Safronova, U. I. Safronova and S. G. Porsev, Phys. Rev. A 87, 032513 (2013).


PP-29

Ion-pair dissociation dynamics in electron collision with

carbon dioxide probed by velocity slice imaging

Narayan Kundu*, Anirban Paul and Dhananjay Nandi

Indian Institute of Science Education and Research Kolkata, Mohanpur, WB-741246.

*[email protected]

In low-energy electron-molecule interaction, dissociative electron attachment (DEA:

energy ≤ 15 eV) and ion-pair dissociation (IPD: 15 eV ≤ energy ≤ 100 eV) are the two well

established inelastic phenomena. IPD occurs when the incident electron partially transfers its

kinetic energy to the molecule and leaves it to one of the neutral super-excited ion-pair states

which ultimately dissociates into a cation and an anion. The dissociation dynamics of these

super-excited states with internal energy greater than the first ionization potential energy of

that particular molecule in the ionization endurance are much different from those of the lower

ordinary states excited below about ionization thresholds [1] and such states can be accessed

by either electron or photon collisions with the isolated molecules.

In electron collision with CO2 the ion-pair states can give rise to momentum matched anion

and cation products,

Figure 1. (a) Ion yield curve of O-/CO2, (b) Velocity slice image at 25 eV incident electron

energy & (c) Kinetic energy distributions of O- ions at different incident electron energies.

Only O- formation channel has been studied using time of flight (TOF) mass spectroscopy

in combination with the highly differential velocity slice imaging (VSI) technique. The ion

yield curve (1.a) of O-/CO2 shows that the threshold energy value of IPD is about 17.2 eV

which matches well with thermo-chemically obtained value (18.06 eV) [2]. The VSI (1.b) at

25 eV incident electron energy dictates that most of the O- ions are produced near zero kinetic

energy. No additional variation in kinetic energy distributions (1.c) of O- ions at different

incident electron energies demand only one major process is involved for anion formation. To

study the symmetry of associated ion-pair states, angular distribution (AD) of O- ions are fitted

using the formula given by Van Brunt [3]. Two ion-pair states π and Ʃ have been identified

based on best fitting of AD measurements.

References [1] Y. Hatano, Journal of Electron Spectroscopy and Related Phenomena.119, 107 (2001).

[2] Erman, Karawajczyk and Rachlew-K, Chem. Phys. Lett. 215, 173 (1993).

[3] R. J. Van Brunt, J. Chem. Phys. 60, 3064 (1974).


PP-30

Differential cross section for positron-biomolecules interaction

Nidhi Sinha* and Bobby Antony

Atomic and Molecular Physics Lab, Department of Physics,

Indian Institute of Technology (ISM) Dhanbad, India

*[email protected]

In recent years medical sciences have seen increasing use of positrons in their diagnostic

techniques. Most popular among these methods are positron emission tomography (PET) [1]

and positherapy [2]. Positron-biomolecule interaction thus becomes important and calls for a

proper investigation on such systems, especially in the low energy region. In this work we have

picked two important molecules, pyridine and pyrimidine. Differential cross section (DCS) for

these molecules are presented at different energies ranging from 1 to 20 eV.

Figure 1. Differential cross section of pyrimidine at 1 eV and 20 eV. Solid line:present

results and spheres: Palihawadana et al. [4]

For the present calculations, spherical complex optical potential (SCOP) formalism [3] is used

to compute the differential elastic cross section. Considering the molecular nature of the target

we have adopted effective potential method (EPM) to encompass the molecular structure in

our computations. This approach is introduced for the first time in our work and as can be seen

from figure 1 gives excellent results even at lowest impact energies. Under this approach we

have generated the molecular potential by adding the potential from various scattering centers

available in the molecule. Partial wave analysis is then done to compute the desired cross

section. SCOP method is well known for producing reliable results at intermediate to high

energies. However, modification of SCOP with EPM have extended this range in the low

energies as well. For pyridine no previous data was found for DCS, while for pyrimidine

experimental cross section of Palihawadana et al. [4] are available. The experimental data is

reported for six different energies and present results show very good agreement at each

energy.

References [1] J. Hooker and R. Carson, Annu. Rev. Biomed. Eng. 21, 551-581 (2019).

[2] R. M. Moadel, R. H. Weldon, E. B. Katz, P. Lu, J. Mani, M. Stahl, M. D. Blaufox, R. G. Pestell, M. J.

Charron, and E. Dadachova, Cancer Res. 65, 698–702 (2005).

[3] N. Sinha and B. Antony, J. App. Phys. 123, 124906 (2018).

[4] P. Palihawadana, R. Boadle, L. Chiari, E. Anderson, JR. Machacek, M. Brunger, S. Buckman, J. Sullivan,

Phys Rev A 88(1), 012717 (2013).


PP-31

Quantum coherence in dissociative electron attachment: isotope effect

S. Swain1, E. Krishnakumar2 and V. S. Prabhudesai1*

1 Tata Institute of Fundamental Research, Mumbai 400005 India 2 Raman Research Institute, Bengalure 560080 India

*[email protected]

Dissociative electron attachment (DEA) to H2 has shown the generation of quantum coherence

among negative ion resonances as manifested in the inversion symmetry breaking in the

angular distribution of the H ion [1]. This asymmetry in the angular distribution shows an

isotope effect. The resonant electron attachment to D2 shows the directionally preferred anion

ejection but the overall asymmetry is different in comparison to its lighter isotope (H2). This

is attributed to different dissociation time, which affects the relative phase of two interfering

channels as well as their amplitudes. Conventionally, HD has been treated as a heteronuclear

diatom as the two isotopes have different masses making the center of mass of the molecule

displaced from the midpoint. This is also seen as the energy difference in the dissociative

ionization [2] as well as anion dissociation limits. In such a scenario, what happens to the

interference observed in DEA?

We have measured the velocity slice images (VSI) [3] of H− & D− arising from DEA to HD

around the 14 eV resonance. Both the anions show asymmetry in the angular distribution which

are identical. The backward anion ejection is preferred over the forward one with respect to

the incident electron direction. The asymmetry increases with increase in electron energy.

From this result we confirm that the incident electron is unable to distinguish between H and

D atom of HD molecule and it behaves like a homonuclear diatom.

Figure 1. Velocity sliced images of H− & D− from DEA to HD at 14.5eV electron energy.

In this poster we will describe our results and compare them with those from H2 and D2.

References [1] E. Krishnakumar, V. S. Prabhudesai, N. J. Mason, Nat. Phys. 14, 149 (2018).

[2] E. Charron, A. Giusti-Suzor, F. H. Mires, Phys. Rev. Lett. 75, 2815 (1995).

[3] D. Nandi, V. S. Prabhudesai, E. Krishnakumar, A. Chatterjee, Rev. Sci. Instrum. 76, 053107 (2005).


PP-32

Angular distribution of H- from dissociative electron attachment to H2 at

10eV

S. Swain1, E. Krishnakumar2 and V. S. Prabhudesai1*

1 Tata Institute of Fundamental Research, Mumbai 400005 India 2 Raman Research Institute, Bengalure 560080 India

*[email protected]

Dissociative Electron Attachment (DEA) to H2 is important to astrophysics [1] as well from

basic electron collision point of view. It has been studied by many groups over several decades

in terms of absolute cross section and angular distributions. Three distinct peaks [2] have been

obtained in DEA to H2 at 4eV, 10eV and 14eV. They are identified as due to i) the lowest

attractive ground X2Ʃu+ anion state (4eV process), ii) the repulsive B2Ʃg

+ state (7-13eV process)

and iii) coherent contribution from 2Ʃg+ and 2Ʃu

+ states (14eV process). The 4eV and 14 eV

processes are extensively studied by many groups in terms of absolute cross-section and

angular distribution as the anion fragments are having less kinetic energy (<1eV). The 4eV

resonance is found to show strong temperature dependence [3]. The DEA signal at 14eV is

found to show signature of coherent superposition of two resonances [4] of opposite parity.

The resonance around 10 eV appears as a broad peak due to a steep slope of the potential

energy curve of the underlying anion state in the Frank-Condon region. This resonance

dissociates into H− (1s2) and H (n=1). As the threshold for this dissociation channel is around

3.75eV, the kinetic energies of H– resulting from this resonance ranges from 1.5 – 4.5eV. M

Tronc et al. [5] have measured the angular distribution using conventional turn table technique

in limited angular range. Measuring the angular distribution using recently developed VSI

technique for such a fast moving light ions is a challenge as the measurements are carried out

in the presence of transverse magnetic field used for collimating the electron beam. We have

carried out these measurements using our recently developed VSI spectrometer [6] and figure

1 shows one such VSI image.

Figure 1. Velocity Sliced Images of H− from DEA to H2 at 10eV.

In this poster we will report the kinetic energy and angular distributions of the H− ions

obtained for this resonance in detail.

References [1] S. C. Glover, D. W. Savin, A. K. Jappasen, Astrophys. J. 640, 553 (2006)

[2] E. Krishnakumar, S. Denfl, I. Cadez, S. Markelj, N. J. Mason, Phys. Rev. Lett. 106, 243201 (2011).

[3] M. Allan, S.F. Wong, Phys. Rev. Lett. 41, 1791 (1978).

[4] E. Krishnakumar, V. S. Prabhudesai, N. J. Mason, Nat. Phys. 14, 149 (2018).

[5] M. Tronc, F. Fiquet-Fayard, C Schermann, J. Phys. B: At. Mol. Phys. 10, 305 (1977).

[6] K. Gope, V. Tadsare, V.S. Prabhudesai, E. Krishnakumar, Euro. Phys. J. D. 71, 323017 (2017)


PP-33

Electron ionization cross sections of C2H4 molecule

Pawan Kumar Sharma1* and Rajeev Kumar2

1Research Scholar, Department of Physics, D. J. College, Baraut, Baghpat, Uttar Pradesh, India

250611 2Asst. Prof. Department of Physics, D. J. College, Baraut, Baghpat, Uttar Pradesh, India-250611

1*[email protected],[email protected]

In this paper we have investigated partial and total electron impact ionization cross sections of

C2H4 molecule [1] by using modified Jain-Khare semi-empirical approach Partial integral

ionization cross sections corresponding to various cations formed during the electron impact

shows good agreement with available data and sum of all partial ionization cross sections give

us total ionization cross sections that again show good agreement with available data. Besides

integral ionization cross sections, first time we have evaluated partial and total single

differential cross sections, and double differential cross sections for the ionization of C2H4

molecule [2]. No other results are available for single differential cross sections and double

differential cross sections to compare the present results calculated.

References [1] Toshio IBUKI, Glyn COOPER and C.E. BRION, J. Chemical Physics 129, 295-309(1989)

[2] Rajeev Kumar, Journal of Applied Mathematics & Physics, 3,1671-1678(2015)

mailto:1*[email protected],[email protected]


PP-34

Laser cooling and trapping of neutral 87Rb atoms

Raj Kumar, Neeraj Singh, Anju Pal, Navpreet Kaur and Ajay Wasan*

Department of Physics, Indian Institute of Technology Roorkee, India

*[email protected]

We demonstrate ongoing experiment to construct a laser cooling and trapping system which

consists three pairs of orthogonally intersecting counter-propagating laser beams and a pair

of anti-Helmholtz coil, i.e., magneto-optical trap (MOT), in which atoms are trapped where

magnetic field is zero. The installation of the MOT system is mainly divided into two

categories, vacuum system installation and optical components arrangement setup. Once the

atomic cloud of 87Rb atoms are produced, we have used two types of imaging techniques for

characterizing the atomic cloud. The first technique is the fluorescence imaging for MOT

loading measurement and second is the absorption imaging for number density and

temperature of atomic cloud measurement.

Figure 1. Schematic diagram of MOT and atomic cloud.

The number of atoms in the trap N = (1.04 ± 0.27) × 106 and the trap volume V = (2.98 ± 0.3)

× 10-2 mm3. The temperature of atomic cloud is T = 128 ± 24 µK. In future, we will trap single

Rb atoms for Quantum Computing.

References [1] L. Isenhower, E. Urban, X. L. Zhang and M. Saffman, Phys. Rev. Lett. 104, 010503 (2010).

[2] J. Dalibard and C. Cohen-Tannoudji, J. Opt. Soc. Am. B 6 (11), 2023-2045 (1989).

[3] P.D. Lett, R. N. Watts, W. D. Phillips and H. J. Metcalf, Phys. Rev. Lett. 61 (2), 169 (1988).


PP-35

Angle dependence of WES photoionization time delay from

atoms trapped in a negatively charged cage

S. Banerjee1,* and P. C. Deshmukh2

1Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India

2Department of Physics, Indian Institute of Technology Tirupati, Tirupati, 517506, India *[email protected]

The dynamics of electrons inside atoms and molecules can now be understood in time-domain

due to developments in ultrafast laser technology over the last decade. Techniques like

RABBITT, attoseconds streaking, attoclock etc. have enabled researchers to look into detailed

dynamics of the photoionization process on the attosecond time scale. The theory of time delay

was developed by Wigner [1], Eisenbud [2], and by Smith [3] in the context of potential

scattering. Photoionization, being considered as half scattering process [4], can also be dealt

with applying the same theory. The Wigner-Eisenbud-Smith (WES) photoionization time

delay, being the energy derivative of phase of the complex photoionization matrix element,

provides significant information about electron correlations in the atomic system. The time

delay spectrum carries prominent signatures near Cooper minima [5], autionization resonances

[6] etc. The present study aims at investigating the WES time delay and its angle dependence

for the photoionization from the outer subshells of noble gas atoms confined inside anionic

fullerene cage. Endohedral fullerenes, being the nanoformations of interest in basic and applied

sciences, are important candidates for spectroscopic studies, which has motivated this work. A

few reports on the time delay for photoionization from confined atom [7] and endohedral

anions [8] are available. The present work reports angle dependence of the WES time delay in

the photoelectron yield from such systems.

References [1] E. P. Wigner, Phys. Rev. 98, 145 (1955).

[2] L. Eisenbud, The Formal Properties of Nuclear Collisions, Ph.D. thesis, Princeton University (1948).

[3] F. T. Smith, Phys. Rev. 118, 349 (1960).

[4] P. C. Deshmukh, D. Angom and A. Banik, Invited article in DST-SERC-School publication (NAROSA),

9-28 (2011).

[5] S. Saha, A. Mandal, J. Jose, H. R. Varma, P. C. Deshmukh, A. S. Kheifets, V. K. Dolmatov and S. T.

Manson, Phys. Rev. A 90, 053406 (2014).

[6] P. C. Deshmukh, A. Kumar, H. R. Varma, S. Banerjee, S. T Manson, V. K. Dolmatov and A. S. Kheifets,

J. Phys. B 51, 065008 (2018).

[7] P. C. Deshmukh, A. Mandal, S. Saha, A. S. Kheifets, V. K. Dolmatov and S. T. Manson, Phys. Rev. A

89, 053424 (2014).

[8] A. Kumar, H. R. Varma, P. C. Deshmukh, S. T. Manson, V. K. Dolmatov and A. Kheifets, Phys. Rev. A

94, 043401 (2016).


PP-36

Theoretical investigation on electron impact with halogen diatomic

molecule X2 (X = F, Cl, Br, I)

Hitesh Yadav1*, Minaxi Vinodkumar2, Chetan Limbachiya3 and P. C. Vinodkumar1

1 Department of Physics, Sardar Patel University, Gujarat, India - 388120 2 Electronics Department, V. P. & R. P. T. P. Science College, Gujarat, India – 388120

3 Department of Applied Physics, The M. S. University Baroda, Gujarat, India - 390002

*[email protected]

Halogens are reactive species; hence their experimental investigation is difficult and involves

large uncertainty [1]. Halogen atoms together with their diatomic molecule play an important

role in variety of physical and chemical processes such as plasma physics, troposphere

chemistry etc. Thus, the theoretical study plays an important role in the case of halogen

molecules.

Literature survey [2-4] reveals that electron impact scattering on F2, Cl2 has been extensively

studied at low to intermediated energy range up to few hundred eV only. But the study related

to Br2 and I2 are rare and only one or two cross-sections on electron impact is reported [2].

Also, the total scattering cross section of these diatomic halogens are very limited. In this

scenario, we try to provide the theoretically estimated cross-sections on electron impact with

these halogen molecules from 0.1 eV to 5000 eV, using two different theoretical formalisms:

1) R-matrix via Quantemol-N [5] which uses the UK based R-mol codes for low energy (0.1

eV to 20 eV) and 2) Spherical Complex Optical Potential (SCOP) formalism [6] for cross-

sections beyond the ionization threshold of the respective target to 5000 eV.

Figure 1. Total scatting cross section of Cl2 molecule.

In figure 1. we present a sample result for the total scattering cross section of Cl2 molecule

starting from 0.1 eV to 5000 eV. The present result qualitatively represents the earlier reported

data, but it overestimates the low energy cross section below 5 eV. And beyond 5 eV the

present result is in overall in good agreement with the data available in the literature. The detail

analysis of the work will be presented at the conference.

Dr. Minaxi Vinodkumar acknowledges DST-SERB, New Delhi for Major research project

[EMR/2016/000470] for financial support under which part of this work is carried out.

References [1] T. R. Hayes, R. C. Wetzel and R. S. Frund, Phys. Rev. A 35, 578 (1987).

[2] G. Raju (2012). Gaseous Electronics. Boca Raton: CRC Press, https://doi.org/10.1201/9781315217437

[3] L. G. Christophorou and J. K. Olthoff, J. Phys. Chem. Ref. Data, 28, 131-169 (1999).

[4] Gregório and Pitchford, Plasma Sources Sci. Technol. 21, 032002 (2012).

[5] H. Yadav, M. Vinodkumar, C. Limbachiya and P. C. Vinodkumar, J. Phys. B: 51, 045201 (2018).

[6] H. Yadav, H. Bhutadia, D. Prajapati, H. Desai, M. Vinodkumar and P. C. Vinodkumar, AIP Conference

Proceedings 1953, 140106 (2018): doi: 10.1063/1.503328.

https://doi.org/10.1201/9781315217437


PP-37

Dissociative electron attachment dynamics to nitrogen dioxide

Anirban Paul1,2, Dipayan Biswas1 and Dhananjay Nandi1*

Indian Institute of Science Education and Research Kolkata.

Mohanpur, WB-741246

*[email protected]

Dissociative electron attachment (DEA) and ion pair dissociation (IPD) are two low-energy

electron-molecule collision processes producing anionic fragments. DEA is a two-step

resonant process predominantly observed in case of low-energy (~0-15 eV) electron collision

with molecules. In the first step incoming electron is attached with the parent molecule forming

a temporary negative ion (TNI) that may dissociate into fragments in the second step.

𝑨𝑩 + 𝒆− → (𝑨𝑩−)∗ → 𝑨 + 𝑩−

We are studying dissociative electron attachment to Nitrogen dioxide (NO2) that plays an

important role in upper atmosphere, as the main source of Ozone in troposphere. It is also the

precursor of nitric acid.

Abouaf et al.[1] reported three DEA peaks of O- ion at 1.8, 3.5 and 8.5eV in dissociative

electron attachment to NO2. Using a velocity slice imaging (VSI) spectrometer we have

measured the angular distribution and kinetic energy distribution of O- ions formed at around

~8.5eV resonance peak.

(a) (b) (c)

Fig. 1. (a) Velocity slice image at 8.6eV incident electron energy (b)kinetic energy distributions

of O- ions at different incident electron energies and (c) Angular distribution of O- ion at 8.6eV

incident electron energy.

We have found that most of the O- ions around this DEA peak are produced with very low near

zero kinetic energy. We have also measured the angular distribution of the O- ions and fitted

the curve with the formula given by Ram [2] and the best fit is observed for A1 B2 transition.

References [1] R. Abouaf, R. Paineau, F. Fiquet-Fayard, J. Phys. B: Atom. Molec. Phys. 9, 303-314 (1976).

[2] N. B. Ram, Dissociation dynamics in polyatomic molecules due to electron attachment, Tata Institute of

Fundamental Research (PhD thesis, 2010).



PP-38

Initial results from the 22-pole ion trap experimental set-up

Roby Chacko1, N. R. Behera1, S. Dutta1 and G. Aravind1*

1 Dept of Physics, Indian Institute of Technology Madras, Chennai - 600036

*[email protected]

An experimental setup using 22-pole radio-frequency (RF) ion trap [1] has been developed,

which can be used to study ion interactions at low temperature and low-density regime. Two

different types of ion sources are employed for ion production. These are, Electron-impact ion

source (EIS) [2] and pulsed supersonic expansion plasma ion source. The former is found to

be more efficient compared to the later. Both positive and negative ions are produced via

electron-impact ionization and secondary electron attachment, respectively, using EIS. The

ions are perpendicularly extracted using a beam-bender and guided into the quadrupole mass

spectrometer (QMS) for the mass selection. Mass spectra of both positive and negative ions

from ionized SF6 gas are observed. We used Helium as a carrier with a small admixture of

CH3I to produce negative ions via dissociative electron attachment, using EIS. The mass

spectra of the same are also observed. We have built our own 22-pole RF trap, mounted next

to QMS, to trap ions. Eventually, we have successfully trapped positive ion fragments of SF6

gas at room temperature. In this poster, we shall represent the first mass spectra, produced

using EIS and results of trapping of positive ions fragments ionized SF6 gas. The experiments

to be done in future shall be discussed in the same poster.

Negative ion mass spectra obtained with ionized SF6 gas

References [1] D. Gerlich, Phys. Scr. T59, 256-263 (1995).

[2] L. G. Christophorou (Ed.). Electron-Molecule Interactions and Their Applications (Vol. 1).

Academic Press. p. 6-11. (1984).


PP-39

Study of reaction kinetics of O + XO → X + O2

S. Naskar* and T. K. Ghosh

Department of physics, Diamond harbour women’s University

Sarisha; D.H. Road; South 24 Parganas; West Bengal- 743368. India

*[email protected]

Ab initio calculation have been performed to investigate the reaction kinetics of the ozone

depleting reaction O + XO → X + O2. The atmospheric ozone plays a beneficial role by

absorbing ultraviolet rays coming from the sun. The excessive emission of green house gases

like carbon dioxide (CO2), chloroflurocarbons (CFC) etc. are responsible for ozone depletion

in atmosphere and thereby causing global warming, several hazardous effects on human being

and climate worldwide.

One of the important ozone depleting reaction is

O + XO → OXO or XOO

→X + O2 (X= Cl, Br, I)

We investigate various minimum energy geometries, transition state geometries, of the above

ozone depleting reaction O + XO → X + O2 from theoretical point of view. Using an extensive

correlation consistent basis sets geometries and frequencies have been obtained at the Moller-

Plesset perturbation theory (MP2). QCISD(T) method is used to obtained the energy value.

The spectroscopic properties of different species are calculated and compared with the

available data. To know details about these complexes and their effectiveness in ozone

depletion layer, our data may be helpful.


PP-40

Spectroscopic properties of divalent lead halides

S. Ghosh# and T. K. Ghosh

Department of Physics, Diamond Harbour Women’s University

Sarisha, DH Road, South 24-Pgs, West Bengal-743368, India #[email protected]

For a long time, there is a scientific interest about the divalent Lead halides (PbX2; X=F, Cl,

Br & I) because of their useful applications due to high ionic conductivity in the development

of semiconductor devices, discharge lamps etc. They are used in infrared devices because they

have good application potentials and large diffraction efficiency. PbF2 plays an importance role

in therapeutic application & it is useful because of its transparent nature. In fabrication of

extremely efficient solar cell PbI2 is a pioneer material. In high-energy photon detector for

gamma rays & X-rays, PbI2 is used due to its wide band gap. PbCl2 and PbBr2 have strong

application potential and so they are used specially in infrared devices. The decomposition

effect of lead halides are used in photographic processes because they are decomposed by light

at high temperature.

In this article, Ab initio calculations are done to pursue minimum energy geometries, vibration

frequency, dissociation energies and various spectroscopic properties of divalent lead halides

(PbX2; X=F, Cl, Br & I) using an extensive basis set. The structural parameters and vibrational

frequencies have been studied at the MP2 level of theory. Energy values are obtained at the

QCISD(T) level of theory at their MP2 optimized geometry. Theoretical calculations of these

systems are limited, because of the concerned heavy atoms. From this perspective, our

computed data may deliver information in future.



PP-41

Camphor doped helium nano-droplets in soft X-ray radiation

S. Sen1†, S. Mandal2, R. Gopal3, R. Richter4, M. Mudrich5, V. Sharma1# and S. Krishnan6* 1 Indian Institute of Technology Hyderabad, Kandi 502285, India

2 Indian Institute of Science Education and Research, Pune 411008, India 3 Tata Institute of Fundamental Research, Hyderabad 500107, India

4 Elettra-Sincrotrone Trieste, Basovizza, 34149 Trieste, Italy 5 Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark

6 Indian Institute of Technology Madras, Chennai 600036, India †[email protected] #[email protected] *[email protected]

Helium nano-droplets has been widely used for spectroscopic studies of doped

atomic/molecular species, as it is a weakly interacting matrix for the dopant [1]. In this work,

we studied the interaction of Camphor, an interesting volatile compound, doped helium nano-

droplets with monochromatic soft X-ray radiation (synchrotron radiation) around the C 1s

edge. The photo-electrons and photo-ions generated are studied with coincidence time-of-

flight mass spectrometry (PEPICO) and velocity map imaging(VMI) techniques.

Preliminary analysis suggests, that although the fragmentation pattern of the Camphor

molecule is similar to the previously reported study [2], the ratio of larger fragments is

enhanced in case of the droplets as compared to the gas phase fragmentation. Further, the

photo-ion energy spectra suggest that there is a mass dependent relative decrease in the energy

and the velocity of fragments ejected from droplets from the corresponding gas phase

fragment, as has been previously reported for the SF6 molecule [3,4].

Figure 1. a] Mass spectrum of Camphor doped He nano-droplet and gas phase Camphor.

b] Photo-fragment Energy spectra of gas-phase and droplet specific Camphor fragments.

References [1] D. Buchta et al, J. Phys. Chem. A 117, 4394−4403 (2013).

[2] R.B. de Castilho et al, Rapid Commun. Mass Spectrom. 28, 1769–1776 (2014).

[3] D. S. Peterka et al, J. Phys. Chem. B 110, 19945-19955 (2006).

[4] A. Braun and M. Drabbels, J. Chem Phys. 127, 114303 (2007).


PP-42

Significance of dynamic quadrupole polarizabilities on the determination

of magic wavelengths of the clock transitions in the alkaline-earth metal

ions

Mandeep Kaur1, Sumeet1, B K Sahoo2 and Bindiya Arora1

1 Guru Nanak Dev University, Amritsar, Punjab-143005, India.

2 Atomic, Molecular and Optical Physics division, Physical Research Laboratory, Navrangpura,

Ahmedabad -380009, India

*[email protected]

The role of dynamic quadrupole polarizabilities in the accurate determination of magic

wavelengths of the clock transitions in Ca+, Sr+ and Ba+ alkaline-earth metal ions is

investigated. The scalar and tensor components of dynamic polarizabilities were obtained

using the sum-over-states approach, for which a large number of electric quadrupole matrix

elements were obtained by employing relativistic coupled-cluster theory. The deviations in

these magic wavelengths from our earlier reported values in [1-3], that were evaluated

accounting only for the dynamic dipole polarizabilities in the above clock transitions, are

reported. These changes are shown with reference to small and large applied electric field-

gradients in the experiments. Additional magic wavelengths are revealed when the ratio of the

electric field-gradient to electric field strength exceeds 0.1 in atomic units. Based on these

findings, we propose the use of high electric field-gradient for strong optical trapping of the

aforementioned alkaline-earth metal ions.

Figure 1. Total dynamic polarizability of the ground state and metastable 3D5/2 state for

Ca+ ion. The crossings of curves for two states represent the Magic Wavelengths.

References

[1] J. Kaur, S. Singh, B. Arora, B. K. Sahoo, Phys. Rev. A 92, 031402® (2015). [2] S. Singh, M. Kaur, B. Arora, B. K. Sahoo, Phys. Rev. A 98, 013406 (2018). [3] B. Arora, B. K. Sahoo, Phys. Rev. A 86, 033416 (2012).


PP-43

Electron impact ionization cross section of atoms and molecules using

binary-encounter-Bethe model

Piyush Sinha1,* and Shivani Gupta

1Dept. of Physics, HNB Garhwal University, BGR Campus, Pauri

*[email protected]

Many frontier areas of research such as material analysis, environmental protection, radiation

science, atmospheric physics, plasma diagnostics and astrophysics require data of electron

impact ionization cross section of molecules. Many experimentalists and theoreticians have

compiled the inner shell ionization cross sections data of different molecules by electron

impact. Kim et al had proposed a Binary Encounter Dipole (BED) and Binary Encounter Bethe

(BEB) models to calculate theoretically the electron impact ionization of atoms and molecules.

The approach has proved to be quite successful for the inner shell ionization cross section of

atoms and molecules. The analytical formula of BEB model employs a scaling term involving

the energy of incident particle, binding energy of the target and the kinetic energy of the target.

In the present investigation we have modified the said scaling term and have computed the K-

shell ionization cross sections of various atoms and molecules by electron impact. The results

in the form of the ratios of K-shell ionization cross section to the total ionization cross section

of the molecules in the energy range up to 5000 eV and for atoms up to 1 GeV have been

compared with the available experimental data which show satisfactory agreement.


PP-44

Photoelectron velocity map imaging spectroscopy facility for probing

astrophysical anions

Saroj Barik and G. Aravind*

Department of Physics, Indian Institute of Technology Madras, Chennai, India

*[email protected]

We have successfully built and tested a photoelectron velocity map imaging spectroscopy

setup in our lab. A supersonic discharge ion source employed to produce different kind of

negative ions. The ions are perpendicularly extracted and mass separated by a linear time of

flight mass spectrometer. The desired anion is photo detached in source region of VMI which

is achieved by synchronizing the laser with the anion of interest. The photo detached electrons

are extracted by VMI electrodes which are detected by a position sensitive detector. From the

observed data we can extract the kinetic energy and angular distribution of ejected

photoelectrons. The setup is calibrated using iodine and oxygen anions. We are performing

photoelectron spectroscopy on couple of astrophysical molecules. The result will be presented

in the conference.

Figure 1. Photoelectron spectra of oxygen anion obtained with 355nm photon.


PP-45

Probing molecular chirality via laser-induced electronic fluxes

Sucharita Giri1,2 , Alexandra Maxi Dudzinski2,3,

Jean Christophe Tremblay2,4 and Gopal Dixit1,*

1 Department of Physics, Indian Institute of Technology Bombay, Mumbai 400076 India 2 Institut für Chemie und Biochemie, Freie Universität Berlin, 14195 Berlin, Germany

3 Institut NEEL CNRS/UGA UPR2940, 38042 Grenoble cedex 9, France 4 Laboratoire de Physique et Chimie Théoriques, CNRS-Université de Lorraine, 57070 Metz, France

*[email protected]

The present work focuses on understanding the conditions required to modify the chirality

during ultrafast electronic motion by bringing enantiomers out-of-equilibrium. Different

kinds of ultrashort linearly-polarised laser pulses are used to drive an ultrafast charge

migration process by the excitation of a small number of low-lying excited states from the

ground electronic state of S- and R-epoxypropane. Control over chiral electron dynamics is

achieved by choosing the different orientations of the linearly polarised pulse. We find that

chirality breaking electric fields are only possible in oriented molecules, and that charge

migration remains chiral when the polarisation of the field lies in the mirror plane defining

the enantiomer pair, or when it is strictly perpendicular to it. Ultimately, the presence or the

absence of a mirror symmetry for the enantiomer pair in the external field determines the

chiral properties of the charge migration process.

Figure 1. (a) Charge distribution difference and (b) corresponding electronic fluxes (blue arrows)

for both the S- and R-enantiomers during field-free charge migration, at different times after the laser

pulse linearly polarized in the yz-plane.


PP-46

Penning spectroscopy of ionic molecular cluster in He nanodroplets

Suddhasattwa Mandal1*, Ram Gopal2, Robert Richter3, Marcello Coreno3, Alessandra

Ciavardini3, Alessandro D’Elia4, Bhas Bapat1, Marcel Mudrich5, Vandana Sharma6 and

Sivarama Krishnan7#

1 Indian Institute of Science Education and Research Pune, Pune – 411008, Maharashtra, India 2 Tata Institute of Fundamental Research Hyderabad, Hyderabad – 500107, Telangana, India

3 Elettra-Sincrotrone Trieste, Strada Statale 14-km 163.5, 34149 Basovizza, Trieste, Italy 4 University of Trieste, Department of Physics, 34127 Trieste, Italy

5 Aarhus University, 8000 Aarhus C, Denmark 6 Indian Institute of Technology Hyderabad, Sangareddy – 502285, Telangana, India

7 Indian Institute of Technology Madras, Chennai – 600036, Tamil Nadu, India

* [email protected] # [email protected]

He nanodroplets are traditionally used as nanoscale-sized sub-Kelvin cryostats for hosting

foreign atoms and molecules for high-resolution spectroscopy over a wide spectral range from

infrared to vacuum ultraviolet, where the host He matrix remains transparent to these

radiations. However, when being photoexcited to 1s2p droplet excitation band by 21.6 eV

photon, the host He droplets can ionize the embedded species through inter-atomic relaxation

process known as Penning ionization. We have used this Penning ionization in He droplet to

study the electronic structure and ionization dynamics of ionic molecular cluster of RbI, doped

in He droplet by employing electron-ion coincidence technique using a velocity map imaging

and time of flight spectrometer, operating in tandem. Penning ionization of RbI is evident from

the ion-yield curve of RbI+ as a function of photon energy shown in Fig.1.

Figure 1. RbI+ ion-yield as a function of photon energy. The shaded yellow band shows the

1s2p droplet excitation band.

Although, recent report with acene doped He droplet [1] suggested Penning electron

spectroscopy may be inefficient in revealing the electronic structure of the dopant due to

scattering of Penning electrons with the droplet environment, similar study with acetylene

doped droplet by our group [2] shows otherwise. This work with RbI dopant affirms Penning

electron spectroscopy as a useful spectroscopic tool to investigate the quantum structure of the

dopant in He nanodroplet.

References [1] M. Shcherbinin et al., J. Phys. Chem. A 122, 1855−1860 (2018)

[2] S. Mandal et al [under preparation]

mailto:*%[email protected]


PP-47

Electron interactions with plasma processing gases

Rakesh Bhavsar1,*, Yogesh Thakar1 and Chetan Limbachiya2

1M.N. College, Visnagar-384315, Gujarat, India. 2The M.S. University of Baroda-390001, Vadodara, Gujarat, India.

*E-mail: [email protected]

We have computed inelastic, ionization and excitation cross sections for plasma processing

gases such as TiClx , x = 1,2,3,4[1-2] from ionization threshold to 5 keV. Here we have used

Spherical Complex Optical Potential (SCOP) [3] to compute total inelastic cross sections Qinel

and have used Complex Scattering Potential – ionization contribution (CSP-ic)[4] model to

compute total ionization cross sections Qion and summed total excitation cross sections ∑Qexc.

Comparison of our results are done with available experimental as well as theoretical results

and noticed good agreement wherever available. Total excitation cross sections are presented

first time.

References [1] V. Tarnovsky, R. Basner, M. Schmidt, K. Becker, Int. J. Mass Spectrom 208, 1-5(2001).

[2] R. Basner, M. Schmidt, K. Becker, V. Tarnovsky, H.Deutsch, Thin solid Films 374, 291-297(2000).

[3] M. Swadia et al., Molecular Physics 115, 2521-2527 (2017).

[4] Y. Thakar et al., Planetary and Space Science 168, 95-103(2019).


PP-48

Design of a Penning trap setup for lifetime studies of metastable states in

atomic ions Deepak Chhimwal1*, S. Kumar2, L. Nair1, W. Quint3, C.P. Safvan2 and M. Vogel3

1 Jamia Millia Islamia University, Jamia Nagar, New Delhi

2 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 3GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany

*[email protected]

In this abstract, we present the design of a compact open-endcap cylindrical Penning trap with

permanent magnets as a tool for enabling isolation and manipulation of the charged particles

from an ECR ion source in a well-controlled environment in order to study the lifetime of the

forbidden metastable transitions in highly charged atomic ions example 2P1/2 state of F-like

Ar9+. The proposed experimental setup will allow to benchmark corresponding radiative

lifetime measurements with high significance and with broad range of ion species.

Figure 1. Left: Sectional view of the setup with cryogenic and Penning trap at the centre.

Right: Penning trap assembly with trap electrodes and magnet for ion

confinement.

The experimental setup consists of a mechanically compensated open-endcap cylindrical

Penning trap with an additional capture electrode on either ends. It has an inner radius of

ρ0=4.5mm half endcap separation of z0=3.7mm and gap size between ring and endcap electrode

of zg=0.5mm. We chose specific value of ρ0/z0=1.22mm [1] to make the anharmonic

coefficient of trap potential C4 zero. The electrical insulation between electrodes is provided

by sapphire rings and sapphire blocks. One of the endcap electrodes is split into two segments

to allow magnetron cooling and also for ion cyclotron frequency detection. The Ring segment

is equipped with two, diametrically opposite 3.5 mm holes for detection of fluorescence light.

The complete electrode stack is mounted on three parallel rods. The trap is placed at the

magnetic field centre of a permanent-magnet assembly. The permanent magnet (REM NdFeB)

provides the field strength of the order of 1T for operation of the trap in an appropriate way

[2]. Measurements show that the magnetic field in the region of ± 2.5mm around the trap centre

has homogeneity better than 1%. The trap itself and its cryo-electronics are cooled to liquid

helium temperature by the helium cryo-cooler which maintains 10 K at the magnet, the trap

and the attached electronics as shown in figure 1.

References [1] Sugam Kumar etal, Phys. Scr. 94, 075401 (2019)

[2] V. Gomer etal, Appl. Phys. B 60, 89 (1995)



PP-49

Electron and positron impact ionization cross sections of nitrogen

molecules

Kamlesh Kumar Jat1 and Ghanshyam Purohit1*

1 Department of Physics, University College of Science, Mohanlal Sukhadia University,

Udaipur-313001, India


Ionization of targets such as atoms, ions, and molecules by charged projectiles such as

electrons/positrons has been studied from a long time and has various applications; few may

be listed as diagnostics of fusion plasmas, modeling of physics and chemistry related to

atmosphere, understanding the effect of ionizing radiation on biological tissues etc. The

detailed information about this kind of collision processes are obtained from the triple

differential cross sections (TDCS) obtained through the coincidence study, which has been of

interest since the pioneering work of Ehrhardt group [1]. Coincidence study of TDCS has been

of particular interest since it provides full information about the collision dynamics and

momentum vectors of all the free particles involved in the ionization are determined.

Good amount of ionization cross section studies have been reported for the atomic targets [2].

From last decade the molecular targets have also been studied for the ionization processes [2,

3] as well as electron momentum spectroscopy studies [4]. We report the results of our recent

work on calculation of electron and positron impact ionization cross sections based on distorted

wave Born approximation formalism (DWBA) for N2 molecules [5]. We will review briefly

the status of charged particle ionization processes from nitrogen molecules in different

geometrical and kinematical conditions. We will discuss the salient features of TDCS which

are projectile charge dependent.

References [1] H. Ehrhardt, K. H. Hesselbacher, K. Jung, and K. Willmann, J. Phys. B 5, 1559 (1972).

[2] D. H. Madison and O. Al-Hagan, J. At. Mol. Opt. Phys. 2010, 367180 (2010).

[3] E. Ali, K. Nixon, A. J. Murray, C. G. Ning, J. Colgan and D. Madison, Phys. Rev. A 92, 042711 (2015).

[4] N. Watanabe, S. Yamada and M. Takahashi, Phys. Chem. Chem. Phys. 20, 1063 (2018).

[5] G. Purohit and D. Kato, J. Phys. B: At. Mol. Opt. Phys. 51, 135202 (2018).


PP-50

Electron induced processes on plasma relevant materials – Be and W

atoms

Kailash Chandra Dhakar and Ghanshyam Purohit*

Department of Physics, University College of Science, Mohanlal Sukhadia University, Udaipur-

313001, India


The ionization cross sections are essential in the modeling of plasma in fusion research.

Beryllium (Be) is one of the materials which is directly exposed to the plasma components in

the International Thermonuclear Experimental Reactor (ITER) [1]. Formation of gas-phase

Be in various charge states and of hydrides of Be, takes place when the erosion of Be walls

occurs in contact with the hot plasma containing hydrogen and its isotopes. Electron collision

processes on the beryllium and its charged states play an important role in the fusion edge and

diverter plasmas. The tungsten (W) and tungsten based materials have also been recommended

as one of the materials to be used as plasma facing components for the International

Thermonuclear Experimental Reactor (ITER) [1], and it is also been used in the number of

current tokamaks such as JET, ASDEX-Upgrade and DIII-D. Electron induced processes are

prevalent in such magnetic fusion devices in a wide range of energies.

We will review and discuss electron induced processes on Be and W atoms. Total cross

sections have been reported for the Be and W atoms and their charged states [2-5]. We will

report the electron impact total cross sections for Be and W atoms in this communication [6].

The cross sections have been calculated in the distorted wave approximation using potential

generated by Hartree-Fock methods [7-8].

References [1] G. Federici, Phys. Scr. T 124, 1 (2006).

[2] J. Colgan, S. D. Loch and M. S. Pindzola, Phys. Rev. A 68, 032712 (2003)

[3] S. D. Loch, J. A. Ludlow, M. S. Pindzola, A. D. Whiteford and D. C. Griffin, Phys. Rev. A 72, 052716 (2005).

[4] M. S. Pindzola, S. D. Loch and A. R. Foster, J. Phys. B: At. Mol. Opt. Phys. 50, 095201 (2017).

[5] F. Blanco, F. Ferreira da Silva, P. Limao-Vieira and G. Garcia, Plasma Sources Sci. Technol. 26, 085004

(2017).

[6] G. Purohit, D. Kato and I. Murakami, Plasma and Fusion Research 13, 3401026 (2018).

[7] R. D. Cowan, The Theory of Atomic Structure and Spectra (University of California Press, Berkeley, 1981).

[8] A. Bar-Shalom et al., J. Quant. Spec. Radiat. Transf. 71, 169 (2001).


PP-51

Exploring quasi molecular phenomenon using heavy ion heavy atom

collisions

R. Gupta1,2, C. V. Ahmad1,2, K. Chakraborty1,2, D. Swami3, G. Sharma4 and P. Verma1*

1 Department of Physics, Kalindi College, University of Delhi, New Delhi-110008 2 Department of Physics and Astrophysics, University of Delhi , New Delhi-110007

3 Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi-110067 4Department of Physics, Government Engineering College, Ajmer, Rajasthan-305001

*[email protected]

During a close and adiabatic heavy ion heavy atom collision, with a decrease in inter-nuclear

distance, the inner shell electrons adjust continuously and adiabatically to the combined time

varying two center nuclear potential of the collision partners. A transient collision molecule or

quasi-molecule is formed for the inner shell electrons during the collision. Such a quasi-

molecule has a united atomic charge ZUA=Z1+Z2 (subscript 1 for projectile and 2 for target)

and if Z1 and Z2 are such that ZUA ≥ 100, superheavy elements can be explored [1,2].

Investigation of projectile energy and target thickness dependence of inner shell ionization

cross sections of 73≤Z2≤83 targets irradiated by 70-120 MeV Agq+ (5≤q≤12) ions have been

recently performed using the 15UD Pelletron at Inter University Accelerator Centre (IUAC),

New Delhi. The collision induced X-Rays from both collision partners were measured using

solid state detectors (see Figure 1). X-Ray energy shifts and altered intensity ratios, indicating

the presence of spectator vacancies, have been observed giving evidence of multiple ionization

of target atoms [3,4]. Additionally, X-Ray production cross sections and target to projectile

intensity ratios have shown enhancements when observed as a function of target atomic

number Z2. These observations can be understood qualitatively within the framework of quasi

molecular phenomenon [1,2]. This considers formation of transient quasimolecules, for the

inner shell electrons during the collision, with united atomic number 120≤ZUA≤130 for the

present collision systems, such that the inner shells of the collision partners become coupled

to each other through correlations with energy levels of corresponding ZUA. These have been

studied using diabatic correlation diagrams for Ag-Z2 (73≤Z2≤83) combinations to understand

the experimental observations.

Figure 1. X-Ray spectrum of 120 MeV Ag9+ on 50 µg/cm2 Au target.

References

[1] J. S. Greenberg et al. High-Energy Atomic Physics—Experimental. In: Bromley D.A. (eds) Treatise on

Heavy-Ion Science. Springer, Boston, MA (1985).

[2] P. Verma et al., NIM B 245, 56–60 (2006); Rad. Phys. and Chem. 75, 2014–2018 (2006); Phys. Scr. T144,

014032 (2011).

[3] W. Uchai et al., J. Phys. B: At. Mol. Phys. 18, L389-L390 (1985).

[4] P. Verma et al., Physica. Scripta. 61, 335 (2000); J. Phys.: Conf. Ser. 875, 092029 (2017).


PP-52

Detailed collisional radiative model for laser produced Zn plasma

Shivam Gupta1*, Reetesh Kumar Gangear2 and Rajesh Srivastava1

1 Department of Physics, Indian Institute of Technology Roorkee, Roorkee, India 2 Department of Physics, Indian Institute of Technology Tirupati, Tirupati, India

*[email protected]

An intricate collisional radiative (CR) model is developed including all the important processes

for the laser induced zinc plasma. The electron impact excitation and de-excitation of several

fine structure levels of Zn play a dominant role in the laser induced plasma and their cross-

sections are needed. In view of this, an extensive calculation is performed to obtain the electron

impact excitation cross-sections of the large number of fine structure transitions of zinc atom.

The cross-sections of Zn are calculated and presented for the excitations from its ground state

4s2 (J=0) as well as from the 4s4p excited state to the various fine structure levels of different

excited states using fully relativistic distorted wave theory. In the calculation relativistic multi-

configuration bound target atomic wave functions are obtained through GRASP2K program

using 4s2, 4s4p, 4s5s, 4s5p, 4s4d, 4s6s, 4s6p, 4s5d, 4s7s and 4s7p configuration state functions

while the projectile incident and scattered electron distorted wave functions are obtained by

solving the relativistic Dirac equations. Further, the calculated cross-sections are incorporated

in the CR model for the plasma characterization as the various rate coefficients are linked

through their corresponding cross-sections. The model gives the state population distribution

of the fine structure energy levels of the neutral Zn atom considered in the model and from

which the intensities of the line emissions are obtained. The calculated intensities from the CR

model for the four emission lines (334.5 nm, 468 nm, 472 nm, and 481 nm) are matched with

the spectroscopic measurements [1] and the plasma parameters viz. electron density (ne) and

electron temperature (Te) are evaluated. The plasma parameters are calculated at different

ambient pressures in the range of 0.05–10 Torr [2].

References [1] N Smijesh, Reji Philip, J Appl Phys 114, 093301, (2013).

[2] S. Gupta, R. K. Gangwar, R. Srivastava, Plasma Sources Sci Technol 28, 095009 (2019).


PP-53

Saturated absorption spectroscopy of molecular iodine for frequency

stabilization of 739 nm laser

Lakhi Sharma1, 2, A. Roy1, 2, S. Panja1, 2 and S. De3,*

1 CSIR- National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012, India 2 Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India

3 Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune-411007,

India

*[email protected]

Frequency stabilization of lasers is essential in many atomic, molecular and optical physics

experiments. Our experiment aims at developing a singly trapped, laser cooled Ytterbium ion

(171Yb+) based optical frequency standard at 467 nm. Ion cooling is obtained by driving the 2S1/2 ↔

2P1/2 transition using 369.5 nm (νC) beam which is obtained from a second harmonic

generation (SHG) laser at fundamental frequency of 739 nm. Additionally, νC + 2.1 GHz and

νC + 14.7 GHz are also used in the process. For probing the said transition, the 739 nm laser

therefore has to be frequency stabilized which is done with respect to molecular iodine (I2)

reference. In this work, we discuss the saturated absorption spectroscopy (SAS) of I2 for

stabilization of the 739 nm ECDL laser. The SAS optical set-up is shown in Figure 1(a). On

focusing counter-propagating pump and probe beams of power 10.6 mW and 1.5 mW

respectively into a 30 cm long Iodine (I2) vapor cell heated to 420oC with a cold finger at 30oC,

and scanning the laser frequency from 405.65395 THz to 405.65518 THz, we obtain the

molecular iodine Doppler free spectroscopy as shown in Figure 1(b). The pump beam is double

passed through an 80 MHz AOM before entering the vapor cell. For effective detection of the

weak signals, the pump is frequency modulated at 60 kHz using the AOM and the signal from

the photodiode is demodulated using a Lock-in Amplifier. As can be seen, six Doppler free

features are present in this region centered at 739.03475 nm, 739.03421 nm, 739.03394 nm,

739.03367 nm, 739.03341 nm and 739.03314 nm and they overlap well with their derivatives

in the lock signal. The Full width at half maximum (FWHM) for these peaks are approximately

13 MHz, 24 MHz, 31 MHz, 17 MHz, 29 MHz and 16 MHz, respectively. As compared to the

measured Doppler broadened width of ≈ 930 MHz at 420oC, the Doppler free spectra obtained

by this technique is of the order of a few tens of MHz. Using Pound-Drever Hall technique,

the laser’s frequency can be locked with respect to the Doppler free features 1, 4 or 6, which

is in progress.

Figure 1: (a) Optical set-up for SAS of I2, (b) I2 SAS profile (red) with Doppler free peaks

marked 1 – 6 with the corresponding Error signal at modulation frequency 60 kHz (blue).


PP-54

Strong field ionization from atoms and nano-tips in structured

beams Abhisek Sinha1 , Debobrata Rajak2 , Sanket Sen1, Ram Gopal2 and Vandana Sharma1*

1IIT Hyderabad, Sangareddy, Telangana 2TIFR Hyderabad, Gopanpally, Telangana

*[email protected]

Studies of strong field ionization of atoms have revealed the existence of a plateau in the photo

electron spectra (PES)[1-4]. This was attributed to the rescattering of electrons from the parent

ion and has been successfully described by the Simple Man’s Model (SMM)[5]. This model

along with the strong field approximation, could adequately describe cut offs of the energy

spectra in atoms. The same model is used to describe the ionization in metal nano tips. In the

following work, we obtained the total electron yield as a function of the intensity of the beam.

Furthermore, we used LG beams to compare the total yield with Gaussian beams.

The experimental setup consists of a time-of-flight spectrometer. Laser light is focused on the

gas jet and the emitted electrons are detected using a MCP detector. The time of flight of the

electrons are recorded and the yield is then calculated. The same experiment is then repeated,

but this time replacing the gas target by a metal nano tip.

When fitted with the equation

𝑊 = 𝛼𝑛𝐼𝑛

where, 𝑊 is the photoelectron yield. 𝛼𝑛 is the cross-section for n photon ionization and I is the

intensity, we see that there is a difference in the value of n at metal nano tips for Gaussian and

LG beams. The same is not true when we go to atomic scales as the value of n is seen to be the

same in both the types of beams for Argon.

References [1] Allen, Les, et al. "Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser

modes." Physical Review A 45.11, 8185 (1992).

[2] Paulus, G. G., et al. "Plateau in above threshold ionization spectra." Physical review letters 72.18, 2851

(1994).

[3] Becker, W., et al. "The plateau in above-threshold ionization: the keystone of rescattering physics." Journal of

Physics B: Atomic, Molecular and Optical Physics 51.16, 162002 (2018).

[4] Paulus, Gerhard G., et al. "Rescattering effects in above-threshold ionization: a classical model." Journal of

Physics B: Atomic, Molecular and Optical Physics 27.21, L703 (1994).

[5] Muller H. G., and van Linden van den Heuvell B. “Multiphoton Processes”. Proceedings of ICOMP 4 ed. S. J.

Smith and P. L. Knight (Cambridge: Cambridge University Press) pp 25–34”(1988)



PP-55

Iron impurity behavior in the ADITYA tokamak

S. Patel1,*, A.K. Srivastava1, M. B. Chowdhuri2, R. Manchanda2, A. Bhattacharya4,

J. V. Raval3, U. Nagora2, P. K. Atrey2, R. L. Tanna2, J. Ghosh2,3 and ADITYA Team2

1Pandit Deendayal Petroleum University, Raisan, Gandhinagar 382007, India

2Institute for Plasma Research, Gandhinagar 382428, India 3HBNI, Anushakti Nagar, Mumbai 400094, India

4Indian Institute of Technology Kanpur, Kanpur 208016, India

*[email protected]

Iron (Fe) impurity behaviour and transport in ADITYA tokamak plasma has been investigated

by modeling the observed VUV spectral lines at 28.41 nm from Fe14+, and 33.54 nm and 36.08

nm from Fe15+. It has been observed that the intensities of the Fe emissions decrease with an

increase in plasma electron density. The observed spectral emission and the intensity ratio of

Fe14+ and Fe15+ impurity ions from two discharges having relatively low and high plasma

density are modeled using a one-dimensional impurity transport code STRAHL It shows that

the observed spectral line emission can be simulated using the same ratio of the convective

velocity to the diffusion coefficient v/D radial profile, but with two different iron concentration

values. The ratio v/D varies from the value of -0.22 m−1 at the plasma normalized radius 𝜌 =

0.2 to a maximum value of -0.35 m−1 at 𝜌 = 0.6. The obtained diffusion coefficient for Fe

impurity ion in the core region is well explained in using neo-classical transport in the Pfirsch–

Schluter regime. While the diffusion coefficient in the edge region, which is large by two

magnitudes as compared to core region is explained using ion temperature gradient turbulence.



PP-56

Electron partial wave analysis of electron scattering from argon atoms

David Joseph and Naveen Chahal

Department of Physics,

Guru Jambheshwar University of Science and Technology, Hisar, Haryana125001


Electron scattering is important in many physical process in Physics, especially the electron induced

excitations in laser systems and semiconductors. It is also important in plasma temperature

measurements. Argon atom having about eight laser transitions is technologically interesting atomic

system. Relativistic Partial wave analysis has been used to study the scattering from central interaction

potential V(r) using the ELSEPA code developed by F Salvat, A Jablonski and C Powell [1]. Semi

empirical correlation polarization potential is used to get the interaction between the electrons with the

atomic states for energies less than 10KeV. To simulate the processes experimentally, we have been

setting up a scattering chamber 80 cms ID and 53 cms height and with four ports (Fig:1). This has been

shielded using the nu-metal covering. A goniometer is being designed for incorporating the electron

gun, angle resolved goniometer, and the Cylindrical mirror Analyzer (CMA). Argon gas will be used

as the target Angle resolved studies will be undertaken to study processes like e-2e collision [2],

excitation process -all in a spectroscopic point of view [3]. A schematic picture of the experimental set

up is shown below (fig:2). The electron gun will be collinear to the faraday cup. The scattered flux will

be collected and analyzed by a CMA and MCA module. Plane wave analysis will be used to analyze

the experimental data obtained

Fig 2 Schematic diagram of the collision Fig:1 Scattering chamber which is being set up experiential set up

References [1] F Salvat, A Jablonski and C Powell, Compute Science Communications 165, 157 (2005)

[2] Y Khajuria and D N Tripathi Phys Rev A 59, 1197 (1999)

[3] R K Singh, Thesis, BHU, “Electron –Impact processes in Gaseous and solid targets at keV energies (2002)


PP-57

High harmonic generation in bichromatic inhomogeneous

pulses

Ankur Mandal1,2,* and Pranawa C. Deshmukh2,3

1Department of Physics, Indian Institute of Science Education and Research Mohali,

Manauli, 140306, India 2Department of Physics, Indian Institute of Science Education and Research Tirupati,

Tirupati, 517507, India 3Department of Physics, Indian Institute of Technology Tirupati,

Tirupati, 517506, India *[email protected]

Chirp pulse amplification and high harmonic generation (HHG) accelerated the studies on light

matter interaction in atomic scale resolution [1, 2]. The intuitive mechanism as described by

three step model provides a playground for modifying the harmonic production [3, 4]. Many

schemes have been implemented both theoretically and experimentally to enhance and extend

the cut-off frequency.

Spatial inhomogeneity of the interacting electromagnetic radiation occur spontaneously in

nanostructures. This allows experimentalists to achieve about three order of magnitude field

enhancement hence a low intensity access to attoscience [5].

Here we show the interaction of atom with two-color infra-red femtosecond field with spatial

inhomogeneity.

Figure 1: Harmonic spectrum for bichromatic spatially inhomogeneous electromagnetc fields

(red dashed) for relative phase difference in the two color fields, ∅ = 0. Corresponding

homogeneous cases are shownin blue line.

In Fig. 1 one sample plot is presented where we can see substantial increment of cut-off. This

incrementis highly sensitive to the relative phase of the two color fields. Maximum

enhancement of the cut-off is observed at zero relative phase difference in the two color fields.

References [1] R. Pazurek et al, Rev. Mod. Phys. 87, 765 (2015).

[2] F. Krausz and M. Ivanov, Rev. Mod. Phys. 81, 163 (2009).

[3] P. B. Corkum, Phys. Rev. Lett. 71, 1994 (1993).

[4] C. Winterfeldt et al, Rev. Mod. Phys. 80, 117 (2008).

[5] S. Kim et al, Nature 453, 757 (2008).


PP-58

Electron-impact cross sections of isovalent AlCl & AlF molecules from

0.1~eV to 5~keV

S. Kaur1*, A. Bharadvaja2 and K. L. Baluja3 1 SGTB Khalsa College, Department of Physics, University of Delhi, Delhi -7, India

2 Bhaskaracharya College of Applied Sciences, Department of Physics, University of Delhi, Delhi-75. 3 (Formerly) Department of Physics and Astrophysics, University of Delhi, Delhi - 7, India

*[email protected]

Closed-shell diatomic molecules, with the univalent aluminium have been detected in

astrophysical environments as exemplified by the Aluminium monofluoride (AlF) and

Aluminium monochloride (AlCl) species. They become quite stable at high temperatures in

the gas phase [1]. AlF lines have been observed in the spectra of umbrae of sunspots [2] and

both AlCl and AlF have been detected in the envelope of the carbon-rich star IRC +10216 [3].

Thus AlCl and AlF being astrophysically very viable we have studied the electron-impact cross

sections of isovalent AlCl & AlF molecules from 0.1~eV to 5~keV

The study of electron-molecule collision is of crucial importance in the understanding and

modelling of natural and technological plasmas, astrophysical processes, planetary

atmospheres and many other fields [4]. This essentially means that a comprehensive set of

accurate electron- molecule collision cross section data is required over a wide range of energy

values.

The ab-initio R-matrix approach is used in one energy domain (less than the ionization

potential) whereas the semi ab-initio Single Center Expansion (SCE) formalism in other

energy domain (ionization threshold to 5 keV). The molecular wavefunctions of the targets are

obtained from the multi-center expansion of the Gaussian-type orbitals within single

determinant Hartree-Fock self-consistent field scheme. The multipole expansion of the target

at center of mass includes the dipole and quadrupole terms. In SCE approach, potentials are

approximated by their local behaviour. The potential included to model the interactions

consists of static, correlation-polarization and exchange effects.

The electron impact ionization cross sections and the excitation cross sections are obtained

using the Binary-Encounter-Bethe model and the R-matrix approach respectively. The electron

excitation cross sections include contributions from both spin-allowed and spin forbidden

transitions. The elastic and inelastic cross sections are summed to obtain the total cross

sections. The elastic, total and momentum transfer cross sections obtained from two

approaches match smoothly near ionization threshold. Further, we also compute the differential

cross sections. The SCE study is also performed in different models. This helped in

understanding the effect of dipole moment and polarization in the scattering problem.

References [1] S. Petrie, J. Phys. Chem. A 102, 7834 (1998)

[2] S. P. Bagare, K. B. Kumar, N. Rajamanickam , Sol. Phys. 234, 1 (2006)

[3] M. Agúndez, J. P. Fonfría, J. Cernicharo, C. Kahane, F. Daniel, M. Guélin, A&A 543, A48 (2012)

[4] Y. Itikawa, Molecular Processes in Plasmas Collisions of Charged Particles with Molecules, (Springer 2007)


PP-59

Positron impact ionization cross sections from pentane isomers

Vardaan Sahgal1, A. Bharadvaja1, S. Kaur2* and K. L. Baluja3

1 Bhaskaracharya College of Applied Sciences, University of Delhi, Delhi-75. 2 SGTB Khalsa College, Department of Physics, University of Delhi, Delhi -7, India

3 (Formerly) Department of Physics and Astrophysics, University of Delhi, Delhi - 7, India

*[email protected]

The elementary particles like electron and positron are used as projectiles in the scattering

phenomenon. Though positron is an antiparticle of electron, its collision physics greatly differs

from electron due to the non-applicability of Pauli Exclusion principle. The positron impact

ionization may result in either in the direct ionization of target or may result in positronium

formation. The latter is absent in case electron is taken as projectile.

Though several methods exist to estimate electron impact ionization cross sections [1,2], no

such methods seems to exist for positron impact ionization process. We present a simple

analytic formula based Binary Encounter formalism to estimate positron impact ionization

cross sections from pentane isomers. A very good agreement is observed with the available

results [3]. The results for pentane isomers are presented. However, the work is in progress to

further simplify the expression without compromising on results.

References [1] Y.-K. Kim and M. E. Rudd, Phys. Rev. A 50, 3954 (1994).

[2] H Deutsch, H, K. Becker, R. Basner, M. Schmidt, M and T.D. Mark. J. Phys. Chem. A 102, 8819 (1998).

[3] N. Sinha and B. Antony, Molecular Physics 117:18, 2527, (2019).


PP-60

New ultrafast laser and instrumentation facility at PRL Ahmedabad for

femtosecond and attosecond science

R. K. Kushawaha*, Madhusudhan P, Rituparna Das, Pranav Bhardwaj, Swetapuspa

Soumyashree, Pooja Chandravanshi and Nimma Vinitha

Physical Research Laboratory, Ahmedabad

*[email protected]

New CEP stabilized ultrafast laser (25fs, 800nm, 10mJ at 1KHz & 3.6mJ at 5KHz), Multi-

plate Velocity Map Imaging Spectrometer, Grating-eliminated no-nonsense observation of

ultrafast incident laser light e-fields (GRENOUILLE) and Spectral Phase Interferometry for

Direct Electric-field Reconstruction (SPIDER) have been installed and functional at new

femtosecond laser lab in PRL Ahmedabad. This is unique lab in India in term of facility. This

lab is established in cleanroom (ISO 7, 10000 grade) with temperature (± <0.05 degree

Centigrade) and humidity (50 ± 5 RH). All optical equipments are installed on optical tables

which are installed on anti-vibration floor isolation area. Recently a femtosecond pump-probe

experiment has been for molecular alignment similar to this reference [1, 2]. In This

conference, recent results on molecular alignment on N2 and CO2 using ultrafast pulses will be

presented. We solved the time dependent Schrodinger equation for CO2 alignment in field-free

case. The result is shown in figure 1. The experimental and theoretical results will be presented

in this conference.

Figure 1. Theoretical result on CO2 alignment with respect to polarization axis using

femtosecond pulses in pump-probe spectroscopy.

References [1] Henrik Stapelfeldt, REVIEWS OF MODERN PHYSICS 75, (2003)

[2] Xiaoming Ren, Varun Makhija, Hui Li, Matthias F. Kling, and Vinod Kumarappan Phys. Rev. A 90, 013419

(2016)



PP-61

Edge temperature and density measurements in ADITYA-U Tokamak

with helium spectral line intensity ratio

Tanmay Macwan*1,2, Sharvil Patel1,3, Nandini Yadava1,4, Ritu Dey1, Kaushlender Singh1,2,

Suman Dolui1,2, Rohit Kumar1, Suman Aich1, Malay B Choudhary1, Ranjana Manchanda1,

R. L. Tanna1, K. A. Jadeja1, K. M. Patel1 and J. Ghosh1,2

1 Institute for Plasma Research, Gandhinagar 382 428 2 Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400 085

3Pandit Deendayal Petroleum University, Gandhinagar 382 007 4The National Institute of Engineering, Mysuru, 570 008

*Email: [email protected]

Edge tokamak plasma is known to be highly turbulent which causes the particle transport

across the equilibrium magnetic field. The turbulence is caused by the inherent gradients in

density and temperature profiles of the tokamak plasma. This edge turbulence is dominated by

various drift wave turbulence which causes fluctuations in the floating potential, density and

temperature [1]. In order to characterize these fluctuations and the corresponding modes, one

needs an accurate measurement of the edge plasma parameters such as floating potential,

density and temperature. These can be measured by a Langmuir probe, which provides the

localized measurements. However, this is an intrusive method. Measurement of edge

temperature by helium spectral line intensity ratio method is a non-intrusive technique, which

can complement the Langmuir probe measurements. The Helium singlet-singlet spectral line

ratio (667.8/728.1 nm) is sensitive to density, whereas the singlet-triplet spectral line ratio

(728.1/706.5 nm) is sensitive to temperature [2]. Using these ratios, we have estimated the

ADITYA-U tokamak edge plasma density and temperature during flat-top phase of discharge.

These helium spectral lines are monitored using a photo-multiplier tube detector with

wavelength interference filter during helium gas puffing into edge region of tokamak. The

analysis for number of discharges shows that the edge temperature is about 7-15 eV and the

edge density is 31918 101105 m . These results are in agreement with the Langmuir probe

measurements.

References [1] X Garbet et al., Plasma Phys. Control. Fusion 46, B557 (2004)

[2] M Griener et al., Plasma Phys. Control. Fusion 60, 025008 (2018)



PP-62

Neutral and impurity influx measurement from limiter and wall of

Aditya-U tokamak

Nandini Yadava1, J. Ghosh2, M. B. Chowdhuri2, R. Manchanda2, Sripathi Punchithaya K1, 3,

Ismyil3, N. Ramaiya1, Ritu Dey2, Tanmay Macwan2, S. Patel4, R. L. Tanna2 and Aditya-U

team2

1The National Institute of Engineering, Mysuru 570008, India 2Institute for Plasma Research, Bhat, Gandhinagar 382 428, India

3Manipal Institute of Technology, MAHE, Manipal 576 104, Karnataka, India 4Pandit Deendayal Petroleum University, Raisan, Gandhinagar, 382 007, Gujarat, India

*[email protected]

The understanding of the tokamak edge plasma is very much crucial to achieve the better core

plasma [1]. The hydrogen fuel particle and major impurities entering into the edge plasma

through plasma-surface interaction modify the edge dynamic through the various atomic and

molecular processes. Then the plasma density control and impurity contamination of the

plasma is determined by the influxes of those from the surrounding surfaces. Considering that,

in Aditya-U tokamak, which is having plasma major and minor radius of 0.75 and 0.25,

respectively, particle and carbon and oxygen impurities influxes have been measured using

PMT based spectroscopic diagnostics made of light collecting lens known as collimating beam

probe, optical fiber, interference filter, and PMT detector. The Hα emission at 656.3 nm from

neutral hydrogen, spectral lines at 464.7 from C2+ and 441.6 nm from O1+ ions have been

routinely monitored through various lines of sight terminating on the bottom wall and inboard

side toroidal belt limiter. After converting these signals into the absolute number of emitted

photons, the influxes have been estimated using the atomic data known as S/XB ratio, which

is basically the information on the number of photons emitted by the particle before ionizing.

This quantification has been done for both wall and toroidal belt limiter to understand their

relative contribution in the total influxes into the Aditya-U tokamak plasma.

References [1] P.C. Stangeby and G.M. McCracken, Plasma boundary phenomena in tokamaks, Nuclear Fusion 30.7, 1225

(1990).


PP-63

Diffraction of proton beams by an optical crystal: Kapitza-Dirac effect for

plasma ions with spin

Sushanta Barman and Sudeep Bhattacharjee

Department of physics, Indian Institute of Technology- Kanpur, Kanpur 208016, India

E-mail : [email protected], [email protected]

The Kapitza-Dirac effect is an example of the wave-particle duality of matter, which consists

of the diffraction of material particles by standing wave of light and is analogous to the

diffraction of light by a material grating in optics. Kapitza and Dirac first predicted this

quantum mechanical effect in 1933 [1] for electron beams. In this effect, matter waves get

diffracted by an optical crystal formed by the standing waves of light where the regions of

maximum intensity of the standing wave act like the crystal planes. It is realized that the

diffracted beams are coherent to each other. Hence this type of set-up is important in the

interferometric systems for the coherent mixing of momentum states [2]. Using this effect,

matter-wave interferometers, experiments related to general relativity [3], gravitational waves

[4], and the fine structure constant [5] can be performed with much higher accuracy. The

interaction of matter-wave of charged particles with the standing waves of electromagnetic

radiations, can be used as a testing ground of non-perturbative quantum dynamical systems

[6].

The diffraction of proton beams obtained from plasmas, by an optical crystal formed by

standing waves of laser (Nd: YAG, λ = 532 nm) is studied by simulating the Gaussian wave

packets associated with the incoming protons. The protons interact with the pondermotive

potential of the optical crystal, due to the nonlinear electromagnetic fields in the standing

waves of laser. From the simulation results of the probability distribution, it is observed that

the charged particles get accumulated at some equidistant positions in the transverse direction,

which results in the diffraction patterns. Experiments will be carried out to observe the

diffraction by the optical crystal for proton beams extracted from a microwave plasma system.

It will be interesting to observe the dependence of the diffraction pattern on the spin

polarization states of the proton beams. The results of the spin evolution in the optical crystal

in the presence of external perturbations such as electrostatic and magnetostatic fields will be

presented.

References [1] P. L. Kapitza and P. A. M. Dirac, Proc. Camb. Phil. Soc. 29, 297-300, (1933).

[2] C. Adams, M. Sigel, and J. Mlynek, Phys. Rep. 240, 143-210, (1994).

[3] Qingqing Hu, Jun Yang, Yukun Luo, Aiai Jia, Chunhua Wei, and Zehuan Li, Optik 131, 632 - 639 (2017)

[4] R. Colella, A. W. Overhauser, and S. A. Werner, Phys. Rev. Lett. 34, 1472-1474 (1975).

[5] Rym Bouchendira, Pierre Cladé, Saïda Guellati-Khélifa, François Nez, and François Biraben, Phys. Rev.

Lett. 106, 080801 (2011).

[6] Batelaan H., Rev. Mod. Phys. 79, 929-941, (2007).




PP-64

Electron impact excitation of highly charged iso-electronic series of Ge like

Ba, Te, Sn, Cd ions

P. Malker1 and L. Sharma1* 1Indian Institute of Technology Roorkee

*[email protected]

Atomic structure and collisional properties of the highly charged atomic ion have great

importance in many areas of science and technology such as laser physics, plasma physics and

astrophysics [1]. Since experimental studies on these systems are very limited, the requirement

of atomic data is mostly fulfill by reliable theoretical methods. Moreover, the relativistic and

QED effects play important role in the study of highly charged heavy ions. Therefore, in order

to attain reliable results, these effects must be taken into account. Further, such studies become

even more challenging for open shell Ge-like ions as there are several fine-structure levels in

the ground state.

There are only a few theoretical investigations for atomic structure properties of highly charged

Ge-like ions. For example, recently Hao et al. reported excitation energies, transition rates and

wavelengths for transitions from ground 4s24p2 to excited 4s4p3 and 4s24p4d states of Ge-like

Te, Xe and Ba ions [2]. However, there are no results reported for electron impact excitation

cross sections of the transitions considered in this work. In the present work we have performed

extensive calculations of cross sections for electron impact excitation of Ge-like Ba XXV, Te

XXI, Sn XIX, Cd XVII, ions using fully relativistic distorted wave (RDW) method. We have

considered fine-structure transitions between the ground state having configuration 4s24p2 and

the excited states with configurations 4s4p3 and 4s24p4d. The reliability of our bound state

wavefunctions is ascertained by comparing our results for excitation energies and oscillator

strengths of the transitions with the available theoretical results for Ba XXV and Te XXI of

Hao et al. [2]. The initial and final state wavefunctions of the target ion is taken as multi-

configuration Dirac Fock wavefunction [3]. The continuum wavefuncton for

projectile/scattered electron is obtained by solving Dirac equation using spherically averaged

potential of the ion is initial/final state of the ion as distortion potential. Thus, relativistic effects

are incorporated in a consistent manner in our calculations. Finally, we obtained cross sections

for all the 67 dipole allowed transitions considered in the present work. We have also provided

fitting of our cross sections with the analytical form so that these can be used easily in plasma

models. The detailed results will be presented in the conference.

Reference

[1] J. D. Gilaspy, J. Phys. B: At. Mol. Opt. Phys. 34, R93 (2001).

[2] L. H. Hao, X. P. Kang, and J. J. Liu. Journal of Applied Spectroscopy, Vol. 84, No. 2, May, 2017 (Russian

Original Vol. 84, No. 2, March–April, 2017).

[3] F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Commun. 94, 249 (1996).


PP-65

Dynamics of dissociative electron attachment to ethanol

S. Das1, S. Swain1 and V. S. Prabhudesai1*


*[email protected]

Functional group dependence present in dissociative electron attachment (DEA) allows

selective bond breaking in molecules as a function of electron energy, which holds enormous

potential for practical application like controlled chemical reaction [1]. In this context, there

has been extensive efforts to understand the DEA dynamics that leads to the functional group

dependent site selectivity. One such functional group in organic molecules, which is common

to many biologically relevant molecules is a hydroxyl group. Ethanol or ethyl alcohol is one

of the simpler alcohols that can be studied for these DEA dynamics. So far, DEA measurement

on ethanol based on mass spectrometric studies have reported formation of H−, O−, OH−, C2H5−

ions [2,3,4]. Only one report describing momentum images for heavier ions [5] have concluded

that the production of O– results from a double dehydrogenation of the negative ion resonance

formed after electron attachment. In our study, we have measured the H– as the most

dominating anionic product of DEA having peaks in the ion yield curve at 6.5 eV, 8 eV and

9.5 eV. As can be seen from fig 1. using partially deuterated ethanol (C2H5OD), we have

identified the origin of the 6.5 eV and 8 eV peaks from the O-H site whereas the 9.5 eV peak

is found to be from the C-H site.

Figure 1. Comparison of normalized ion yield curve for H− from ethanol (black square) and D−

(red circles) and H− (blue triangles) from deuterated ethanol

We have carried out the momentum imaging of these ions using velocity slicing technique

and unraveled the dynamics that leads to these selective channels. In this poster we will

present the details of these dissociation channels as well that for the OH− channel.

References [1] V. S. Prabhudesai, A. H. Kelkar, D. Nandi, E. Krishnakumar, Phys. Rev. Lett. 95, 143202 (2005).

[2] M. Orzol, I. Martin, J. Kocisek, I. Dabkowska, J. Langer, E. Illenberger, Phys. Chem. Chem. Phys. 9, 3424 (2007).

[3] B. C. Ibănescu, M. Allan, Phys. Chem. Chem. Phys. 11, 7640 (2009).

[4] V. S. Prabhudesai, D. Nandi, A. H. Kelkar, E. Krishnakumar, J. Chem. Phys. 128, 154309 (2008).

[5] X-D. Wang, C.-J. Xuan, W.-L. Feng, S. X. Tian, J. Chem. Phys. 142, 064316 (2015).


https://pubs.rsc.org/en/results?searchtext=Author%3AMario%20Orzol

https://pubs.rsc.org/en/results?searchtext=Author%3AIsabel%20Martin

https://pubs.rsc.org/en/results?searchtext=Author%3AJaroslav%20Kocisek

https://pubs.rsc.org/en/results?searchtext=Author%3AIwona%20Dabkowska

https://pubs.rsc.org/en/results?searchtext=Author%3AJudith%20Langer

https://pubs.rsc.org/en/results?searchtext=Author%3AEugen%20Illenberger

https://aip.scitation.org/author/Wang%2C+Xu-Dong

https://aip.scitation.org/author/Xuan%2C+Chuan-Jin

https://aip.scitation.org/author/Feng%2C+Wen-Ling

https://aip.scitation.org/author/Tian%2C+Shan+Xi


PP-66

Effect of background static gas on momentum images in velocity slice

imaging of dissociative electron attachment

S. Das1, S. Swain1 and V. S. Prabhudesai1*


*[email protected]

Velocity slice imaging technique is one of the commonly used techniques for momentum

imaging of photodissociation dynamics of molecules. The introduction of this technique for

measuring the momentum distribution of fragment anions produced in low energy electron

collision experiments has revolutionized the understanding of the dissociative electron

attachment (DEA) process [1]. Due to its ability of measuring the angle dependence of the

fragment products it has been very useful in determining the symmetries of the anion

resonances. This has enabled identifying new resonances [2], distinguishing different

overlapping resonances [3] and identifying symmetry based dynamics of the resonances [4].

Usually, in these experiments, effusive molecular beam has been used as the source of the

target molecules in the ultrahigh vacuum chamber where the electron beam is made to cross at

right angles. Such a source of molecules also causes significant contribution from the

background as the effused gas eventually occupies the chamber volume, increasing the

background gas (here we call static gas) pressure which is determined by the effective pumping

speed of the vacuum pumps and the flow rate of the effused gas. In such a scenario, the electron

beam traverses significant length of path through this static gas, which contributes substantially

to the momentum image obtained. As can be seen from figure 1, the contribution of the static

gas affects the quality of the momentum image.

(a) (b) (c)

Figure 1. Momentum images obtained for H− from ethanol from the (a) crossed beam

where the static gas also contributes (b) pure static gas in the absence of molecular beam

and (c) pure crossed beam contribution obtained by subtracting the images

In this poster, we will discuss this effect and its detailed analysis.

References [1] D. Nandi, V. S. Prabhudesai, E. Krishnakumar, A. Chatterjee, Rev. Sci. Instrum. 76, 053107 (2005).

[2] V. S. Prabhudesai, D. Nandi, E. Krishnakumar, J. Phys. B At. Mol. Opt. Phys. 39, L277 (2006).

[3] K. Gope, V. S. Prabhudesai, N. J. Mason, E. Krishnakumar, J. Phys. B At. Mol. Opt. Phys. 49, 015201

(2016).

[4] E. Krishnakumar, V. S. Prabhudesai, N. J. Mason, Nat. Phys. 14, 149 (2018).


PP-67

Theoretical investigation of the electronic structure of HgH+

R. Bala1,*, H. S. Nataraj1, M. Kajita2 and M. Abe3

1 Department of Physics, Indian Institute of Technology Roorkee, Roorkee -247667, India

*[email protected], [email protected] 2 National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795,

Japan

[email protected] 3 Department of Chemistry, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo

192-0397, Japan

[email protected]

A rotational transition X1Σ (J, F) = (0, 1/2) → (1, 1/2) in the 202HgH+ ion has recently been

proposed for frequency standard, in the terahertz region, with an uncertainty below 10-15 [1].

To study the systematic shifts induced in a clock transition (which is a result of the coupling

of states with neighboring electronic, vibrational and rotational states), an accurate knowledge

of spectroscopic constants and molecular properties of the ground and excited states of this

molecular ion is necessary [1]. Except the spectroscopic constants of ground and first excited

electronic state of Σ symmetry [2], there are no other experimental results available for 202HgH+. The available theoretical results are also limited only to the spectroscopic parameters

of the electronic ground-state at the non-relativistic and quasi-relativistic levels [3-5]. In this

context, we have performed 4-component relativistic calculations and obtained potential

energy curves, dipole moment curves, diatomic constants, vibrational and rotational

parameters for the ground and a few low-lying excited states of this ion. The configuration

interaction (CI) method limited to single- and double-excitations is employed together with the

quadruple zeta basis sets. The details of our theoretical investigation together with the results

will be presented in the conference.

References

[1] M. Kajita, R. Bala, M. Abe, J. Phys. B (Under review).

[2] G. Herzberg, Spectra of Diatomic Molecules, Second Edition (D. Van Nostrand), May 1950.

[3] N. S. Mosyagin, A. V. Titov, E. Eliav, and U. Kaldor, arXiv:physics/0101047v4 [physics.chem-ph].

[4] G. Ohanessian, M. J. Brusich, and W. A. Goddard , J. Am. Chem. Soc. 112, 7179 (1990).

[5] U. Häussermann , M. Dolg, H. Stoll, H. Preuss, P. Schwerdtfeger, and R .M. Pitzer, Molecular Physics 78,

1211 (1993).



PP-68

Analysis of visible spectra in tungsten ions observed from electron beam

ion trap

Priti1, Daiji Kato2,3, Izumi Murakami2,4, Hiroyuki A. Sakaue2 and Nobuyuki Nakamura1

1Institute of Laser Science, University of Electro-communications, Tokyo, 182-8585 Japan 182-8585

2National Institute for Fusion Science, Toki, Gifu 509-5292, Japan 3Department of Advanced Energy Engineering Science, Kyushu University, Fukuoka 816-8580,

Japan 4Department of Fusion Science, SOKENDAI, Toki, Gifu 509-5292, Japan

*[email protected]

Atomic data of few times ionized tungsten have great importance due to its prospective

application in diagnostics of edge plasma of the ITER [1]. A large fraction of the divertor

plasmas are expected to contain tungsten ions in charge states mainly from three to fifteen

times ionized (WIV-WXVI). Therefore, emission lines from these tungsten ions are a very

useful tool to determine their concentration, the influx of tungsten sputtered from the wall to

the core plasma and to assess power loss. In addition, the visible transitions of WIX and WX

are the potential candidate for optical atomic clocks. These transitions are supposed to be very

sensitive to the α variation due to level crossing of 4f and 5p levels [2]. However, the candidate

transitions have yet to be experimentally identified.

In literature, to date there are no lines reported for these two ions in the visible region [3].

Therefore, to fill this void visible spectra of WVIII to WX tungsten ions have been recorded

using Compact electron beam ion trap (CoBIT) by our group [4]. To identify the observed

spectra from CoBIT, a fine structure resolved collisional radiative (CR) model is developed.

Electron impact excitation, de-excitation, and radiative decay are taken into account in the rate

balance equation. Since electron density is small (1010cm-3), other recombination processes

viz. radiative recombination, three-body recombination and dielectronic recombination is

ignored in the model. To ensure the identification of lines done by the CR model we have also

performed the accurate calculation of transition energies and transition probabilities within

multi configurational Dirac-Fock using the GRASP2018 [5]. We found that most of the

observed lines are from M1 transitions between lower-lying stares of these ions. Details of the

model and analysis will be presented in the conference.

References [1] J. Clementson et. al., Atoms 3, 407 (2015)

[2] J C Berengut et. al., Phys. Rev. Lett. 105, 120801 (2010)

[3] A. E. Kramida et. al., Data Nucl. Data Tables 95, 305 (2009)

[4] M. Mita et. al., Atoms 5, 13 (2017)

[5] C. Froese Fischer, et. al., Computer Physics Communications 237, 184 (2019)


PP-69

Strongly coupled plasma effect on excitation energies and transition data of

Ca VI

Sunny Aggarwal1,a, Arun Goyal1,b and Man Mohan2

Department of Physics, Shyamlal College, University of Delhi, Delhi-110032, India.

Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India [email protected]

[email protected]

The main goal of the present study is to analyze and estimate the plasma screening effect on

excitation energies and transition data for Ca VI (P-like Ca) under the influence of strongly

coupled plasma. We have employed an ion sphere model (ISM) in flexible atomic code (FAC)

to study and analyze plasma effect in atomic structure. We have presented shift in excitation

energies of lowest 13 levels belonging to the configurations 3s23p3 and 3s3p4 at electron

densities ranges 1022 - 1024 cm-3 under plasma environment. We have also studied transition

wavelengths, transition rates and oscillator strengths at electron densities ranges

1022 - 1024 cm-3 under plasma environment.


PP-70

Plasma screening effect on excitation energies and transition data of

P-like Zn

Arun Goyal1,a , Sunny Aggarwal1,b, Narendra Singh1 and Man Mohan2

Department of Physics, Shyamlal College, University of Delhi, Delhi-110032, India.

Department of Physics and Astrophysics, University of Delhi, Delhi-110007, India [email protected]

[email protected]

The main goal of the present study is to analyze and estimate the plasma screening effect on

excitation energies and transition data for P-like Zn under the influence of strongly coupled

plasma. We have employed an ion sphere model (ISM) in flexible atomic code (FAC) to study

and analyze plasma effect in atomic structure. We have presented shift in excitation energies

of lowest 20 levels at electron densities ranges 1022 - 1024 cm-3 under plasma environment. We

have also studied transition wavelengths, transition rates and oscillator strengths at electron

densities ranges 1022 - 1024 cm-3 under plasma environment.

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