cuijk mepalumbo lect3-4 - radboud universiteit · 2012. 6. 13. · thermal processing 1. diffusion...

PROCESSING

M.E. PalumboINAF – Osservatorio Astrofisico di Catania, ITALY

PROCESSING

Thermal processing Energetic processingThermal processing Energetic processing

Thermal processing

Thermal processing is due to the increase of the temperature of the sample

The main effects of thermal processing are:

1. Diffusion1. Diffusion

2. Segregation

3. Crystallization

4. Sublimation

Thermal processing in space

Young stellar object

Thermal processing

1. Diffusion

H2O deposit at 15 K CO deposit at 15 K CO diffusion at 26 K

wavelength (m)

2.64 2.68 2.72 2.76

wavelength (m)4.65 4.7

Porous ASW

Si substrate

Collings et al. 2003Fraser et al. 2004Palumbo 2006Raut et al. 2007

opticald

ep

th(a

.u.) H

2O deposit

3750 3700 3650 3600

OH dangling bond feature

wavenumber (cm-1)

CO diffusion

Palumbo 2006

2160 2140 2120

0.00

0.05

0.10

0.15

0.20

0.25

0.30

S polarization

wavenumber (cm-1)

optica

lde

pth

CO band profile

CO on H2O at 15 K

after diffusion at 30 K

Palumbo 2006

Thermal processing

1. Diffusion

Collings et al. 2003Fraser et al. 2004Palumbo 2006Raut et al. 2007

Fraser et al. 2004

Thermal processing

2. Segregation

Ehrenfreund et al. 1997, 1998Dartois et al. 1999Boogert et al. 2000Palumbo & Baratta 2000

Ehrenfreund et al. 1998

Thermal processing

2. Segregation


Ehrenfreund et al. 1997

Thermal processing

2. Segregation

CH3OH:CO2=1:1

13CO2 stretching mode 12CO2 bending mode

Dartois et al. 1999

Thermal processing

2. Segregation


Palumbo & Baratta 2000

Segregation doesn’t occurwhen the CO2 concentrationis less than about 10%

Thermal processing

2. Segregation

CO2 stretching mode CO2 bending mode

Spectra in P and S polarization are different thismeans that they are not representative of smallparticle cross section.Laboratory spectra cannot be directly comparedto observed spectra.


Thermal processing

2. Segregation

Laboratory spectra in P and Spolarization are very similar. Thismeans that they are representativeof small particle cross section andcan be directly compared to

13CO2 stretching mode


can be directly compared toastronomical spectra.

3. Crystallization

Thermal processing

Crystalline

Hagen et al. 1983Schmitt et al. 1989Moore and Hudson 1992Hudgins et al. 1993Jenniskens et al. 1995Leto and Baratta 2003

O-H stretching modes in H2O iceLeto and Baratta 2003

Amorphous

lattice modesHudson and Moore 1992

3. Crystallization

O-H stretching modes in H2O ice

Thermal processingSpectra in P and S polarization are different thismeans that they are not representative of smallparticle cross section.Laboratory spectra cannot be directly comparedto observed spectra.

Leto and Baratta 2003

Water ice(H2O)

Water ice shows variousstates of “crystallinity”.

Dartois and d'Hendecourt,A&A 365, 144 (2001)

3. Crystallization

Methyl formateModica and Palumbo 2010

Thermal processing

3. Crystallization

Thermal processing

AcetonitrileAbdulgalil et al. submitted

Thermal processing4. Sublimation

Aftercrystallization

Aftersublimation

Palumbo et al. 1999

Thermal processing4. Sublimation

Pure species Species on pre-adsorbed H2O Species co-deposited with H2O

TPDTemperatureProgrammedDesorption

Collings et al. 2004

Energetic processing

Interaction of cosmic rays with molecular clouds

High density and high extinction stellar radiation does not penetrate molecular clouds

low-energy cosmic rays UV photons

E = keV - MeV E = 6.9-13.6 eV

electrons

E = keV

Cosmic ion and UV fluxes in quiescent regions

Proton flux(1 MeV) = 1.8 cm-2 s-1

(diffuse regions)

(1 MeV) = 1 cm-2 s-1(dense regions)

Mennella et al. 2003, ApJ 587, 727

UV photon flux

(UV) = 8 107 cm-2 s-1(diffuse regions)

(UV) = 1.4 4.8 103 cm-2 s-1(dense regions)

Mathis et al. 1983, A&A 240, L19,Prasad & Tarafdar 1983, ApJ 267, 603;Mennella et al. 2003, ApJ 587, 727

Cosmic ion and UV fluxes in the ISM

Tim e

(years)

UV Irradiation

Flux absorbed energy Dose

eV/cm 2/s eV/cm 2/s eV/mol

IO N Irradiation

Flux absorbed energy Dose

eV /cm 2/s eV/cm 2/s eV/m ol

Colddiffuseclouds

9.6108 5108

(200 Å icem antle)

1107 1.2104

(200 Å icem antle)

(105) 1104 <1

(107) 6 1(107) 1106 3101

(109) 1108 3103

Colddenseclouds

1.4104 1.7103

(200 Å icem antle)

1106 1.2103

(200 Å icem antle)

(105) <1 <1

(107) 4 3

(109) 4102 3102

Moore 1999

Energetic processing in the Solar System

Energy Fluxes (cm-2 s-1)

Solar Photons 2 eV Visible 2.0·1017

4 eV NUV 1.5·1016

6 eV FUV 3.0·1013

Solar Wind (1 AU)1keV H+ 3.0·1081keV H+ 3.0·108

4keV He2+

Solar Flares (1 AU)>1 MeV H+ 1010 (cm-2 yr-1)>1 MeV He2+

Galactic cosmic rays>1 MeV H+ 1-10>1 MeV He2+

Relevant parameters

Target composition poorly known -> analogues

Temperature

Pressure

Ion’s mass very easyIon’s mass very easy

Ion’s energy spectrum impossible --> mechanisms

Flux (cm-2 s-1) lab >> space --> only single ion/photon effects are relevant

Fluence (cm-2 ) comparable

Time researcher’s lifetime << astronomical evolutionary timescale

Laboratorio di Astrofisica SperimentaleCatania

Ion beam Vacuum chamber FTIR spectrometer

Vacuum chamber

In-situanalysis:

IR spectroscopy

Raman spectroscopy

Mass spectrometry

Experimental procedure

Substrate (Si, KBr, CsI)T=10-300 K

IR beam

Background (mid-infrared) at 16 KBackground (mid-infrared) at 16 K(KBr substrate)


SampleT=10-150 K

IR beam

Mid-IR spectrum of the sample as depositedMid-IR spectrum of the sample as deposited(CH3OH at 16 K)


Irradiation of the sampleT=10-150 K

Ions (keV - MeV)Ions (keV - MeV)


Irradiated sampleT=10-150 K

IR beam

Mid-IR spectrum of the sample after irradiation(CH3OH + 200 keV H+ at 16 K)

CO2 COCH4

H2CO


Continuum normalization

τ = - ln (I/I0)

ION IRRADIATION EXPERIMENTS

Target (0.2-6 m) Target (1-30 m)Target (1-20 m)

Ions (30-400 keV)

Ions pass through the target ImplantationIrradiation during deposition

Dose (eV molecule-1)

The dose is the average energy absorbed by the sample

In ion irradiation experiments is given by

Dose (eV molecule-1) = Stopping power (eV cm2 molecule-1) x Fluence (ions cm-2)

In UV photolysis experiments (assuming a monochromatic source) is given by

Dose (eV molecule-1) = Fluence (photons cm-2) x Photon energy (eV) x absorbed photon fraction

column density (molecules cm-2)

Interaction of ions with matter

J.F. Ziegler: SRIM (Stopping and Range of Ions in Matter); TRIM (TRansport of Ions in Matter)

Ion current measurement during irradiation

Brass ring

Brass ring with negative voltage to prevent electron emission

Electrostaticallyscanned ion beamscanned ion beam

The area of the brass ring is equal to the area of the hole.The number of ions passing through the brass ring is equal to the number that hit the ring.

Tothe sample

UV lampsThe flux (photons cm-2 s-1) of UV lamps is notstable and can vary also during a singleexperiment. Therefore it is important tomeasure the flux during each experiment.

A platinum wire can be used to measure theUV flux during photolysis. The number ofphotons cm-2 impinging on the sample iscorrelated to the integrated current C (C)correlated to the integrated current C (C)given by the photoelectric effect at theplatinum wire.

Baratta et al. 2002Leto and Baratta 2003Loeffler et al. 2005Mennella et al. 2006

Absorption coefficients

In principle absorption coefficients can be measured from VUV transmittance spectra

Absorbed photon fraction = 1- e-αx

where α is the absorption coefficient and x is the sample thickness

Absorption coefficient for a given species strongly depends on the wavelength

Absorption coefficient may change during photolysis

In principle absorption coefficients can be measured from VUV transmittance spectra

UV lampsThe spectrum of UV lamps depends onoperating conditions (e.g. pressure in thedischarge tube and gas mixture ratio).

Mu

no

zC

aro

and

Sch

utt

e2

00

3

etal

.19

95

Co

ttin

etal

.20

03

We

stle

yet

al.1

99

5

Effectiveabsorption coefficients

Baratta et al. 2002

Effectiveabsorption coefficients

Effective absorption coefficientsH2O α = 28 m-1

CH3OH α = 12 m-1

CO α = 4.3 m-1

CH4 α = 19 m-1 (low dose)CH4 α = 33 m-1 (high dose)

Baratta et al. 2002Loeffler et al. 2005

Effects of energetic processing

keV-MeV ionsUV photons

frozen gases

Sputtering Structural Chemistry Implantation Residuechanges

Energetic processing1. Sputtering

Brown et al. 1982, 1984Shi et al. 1995Bahr et al. 2001Teolis et al. 2005Seperuelo Duarte et al. 2009, 2010Seperuelo Duarte et al. 2009, 2010Dukes et al. 2011

Seperuelo Duarte et al. 2010

Se= anelastic stopping power


Photodesorption

Westley et al. 1995Oberg et al. 2007, 2009Munoz Caro et al. 2010

H2O

Munoz Caro et al. 2010Fayolle et al. 2011

Westley et al. 2005


Photodesorption

Westley et al. 1995Oberg et al. 2007, 2009Munoz Caro et al. 2010Munoz Caro et al. 2010Fayolle et al. 2011

Oberg et al. 2009

Energetic processing2. Structural changes

Crystalline samples amorphous

Porous ASW compact

Effects of ion irradiation on c-H2O30 keV H+ irradiation of c-H2O

(Leto & Baratta 2003, A&A 397, 7)

700 keV H+ irradiation of c-H2O(Hudson & Moore 1992, ApJ 401, 353)

O-H stretching modes lattice modes

Effects of UV photolysis on c-H2O

Leto and Baratta 2003

Amorphization process

The amorphizationprocess hascomparable crosssection for differentions and Lyman-ions and Lyman-alpha photons.

FA=A(1-e-kD)

Leto and Baratta 2003, A&A 397, 7

Effects of ion irradiation on ASW

1.0

1.2

1.4

wavelength (m)

O-H stretching

op

tica

ld

ep

th

H2O at 16 K

3 6 9 12 15

Palumbo 2005

4500 4000 3500 3000 2500 2000 1500 1000

0.0

0.2

0.4

0.6

0.8

libration

combinationO-H bending

wavenumber (cm-1)

op

tica

ld

ep

th

3780 3760 3740 3720 3700 3680 3660

0.00

0.02

0.04

OH dangling bonds


pol P

op

tica

ld

ep

thas deposited

+6.11013

200 keV H+

cm-2

Leto et al. 1996

3800 3600 3400 3200 3000

wavenumber (cm-1)

op

tica

ld

ep

th


T=80 K+100 keV H+

Raut et al. 2004

Palumbo 2006

Effects of UV photolysis on ASW

Palumbo et al. 2010

Palumbo 2006

Amorphization of silicates

Brucato et al. 2004

Amorphization of silicates

Amorphisation depends on nuclear(elastic) stopping power. UV photonswould not amorphise silicates.

Brucato et al. 2004

Energetic processing3. Chemistry

DIRECT COMPARISON BETWEEN ION IRRADIATION AND UV PHOTOLYSIS

H2O:CO2=1:1 (Gerakines, Moore, Hudson, A&A 357, 793, 2000)

CO (Gerakines and Moore, Icarus 154, 372, 2001)

H2O:CO:CH3OH:NH3 (Cottin, Szopa, Moore, ApJ 561, L142, 2001)

CH4, CH3OH (Baratta, Leto, Palumbo, A&A 384, 343, 2002)

N2 (Hudson and Moore, ApJ 568, 1095, 2002)

C24H12-ice mixtures (Bernstein et al. ApJ 576, 1115, 2002; ApJ 582, L25, 2003)

H2O (Leto and Baratta, A&A 397, 7, 2003)

CO (Loeffler, Baratta, Palumbo, Strazzulla, Baragiola, A&A 435, 587 2005)

Energetic processing3. Chemistry Chemistry in CO ice

Wavelength (m)

Optica

lD

ep

th

13C

16O

2

13C

16O

13C

18O

4.2 4.4 4.6 4.8 5 5.2

Loeffler et al. 2005

2400 2300 2200 2100 2000

13C

18O

2Optica

lD

ep

th

Wavenumber (cm-1)

12C

16O

2

13C

18O

16O

12C

16O SiH

13C

3

16O

2

as deposited

+ UV

+ H+


42

44

46

mole

cule

scm

-2)

13CO

+200 keV H+

45

mo

lecu

les

cm

-2)

13CO

+10.2 eV photons

0 5 10 15

0.0

0.5

1.0

1.5

2.0

2.5

40

42

Colu

mn

Densi

ty(1

016

mole

cule

scm

Fluence (1014

200 keV H+

cm-2)

CO

13CO

2

0 5 10 15 200.0

0.2

0.4

0.6

0.8

40

Co

lum

nD

en

sity

(10

16

mo

lecu

les

cm

Fluence (1017

incident photons cm-2)

13CO

2

Loeffler et al. 2005Loeffler et al. 2005


It is interesting to note that whilethe initial production rate of CO2

per unit energy deposited issimilar for 10.2 eV photons and200 keV protons, the equilibriumCO2 concentration is three timeshigher for ion irradiation. This is


higher for ion irradiation. This isdue to the different ratiosbetween the formation anddestruction cross sections for ionirradiation and UV photolysis.



0.3

0.4C

2H

6

CH4+ 60 keV Ar

++(7 eV/16 amu) at 12 K

abso

rbance

Baratta et al. 2003

Chemistry in CH4 ice

3400 3200 3000 2800 2600

0.0

0.1

0.2

C2H

6

C2H

6

C2H

6CH

4

CH4

C3H

8

C2H

2

abso

rbance

wavenumber (cm-1)

1600 1500 1400 1300 1200

C2H

6

C2H

2C2H

4

C2H

6

wavenumber (cm-1)


Chemistry in CH4 ice

Baratta et al. 2002


Chemistry in N2 ice

Hudson and Moore 2002


Layered samples

CO:H2S

200 keV H+

Studied samples (T=16-20 K)

pure CO

pure H2S

pure SO2

CO/H2S layer

CO:H S=10:1 (mixture 1)

CO:SO2

200 keV H+ COH2S

CO:H2S=10:1 (mixture 1)

CO:H2S=1:10 (mixture 1)

CO/SO2 layer

CO:SO2=5:1SO2

Palumbo et al. 2008, ApJ 685, 1033Garozzo et al. 2008, Pl. Sp. Sci. 56, 1300Garozzo et al. 2010, A&A 509, A67


CO:H2S=10:1 +200 keV H+

Garozzo et al. 2010


Layered samples

CO/H2S layered +200 keV H+

Garozzo et al. 2010


<10-2 eVsputtered species

30-200 keV ions

Water ice on C-rich substrates

Refractory residue oramorphous carbon grains

Thin water ice layer

T=12 KMennella et al. 2004Gomis and Strazzulla 2005Sabri et al. poster at this school


H2O on amorphous carbon grains at 12 K

wavelength (m)

0.05

0.10

op

tica

ld

ep

th

as deposited

3 6 9 12 15

Mennella et al. 2004

4000 3500 3000 2500 2000 1500 1000

0.00

0.05

CO

CO2

wavenumber (cm-1)

op

tica

ld

ep

th

+2.31015

30 keV He+/cm

2

0.00

op

tica

ld

ep

th

H2O2

Composition of icy grain mantles

(with respect to H2O=100)

Origin of solid phase molecules

Freeze out of gas phasespecies (CO)

Grain surface reactions

UV photons

cosmicions

Grain surface reactions(H2O, CH3OH, CH4, H2S, CO2)

Energetic processing of icymantles (CO2 , OCS)

Comparison with observationsOCS band at 2040 cm-1

H2O:CO:H2S=10:5:1 +0.8 MeV H+

Ferrante et al. 2008, ApJ 684, 1210

CO:H2S=10:1 +200 keV H+

Evidence of temperature gradientalong the line of sight.

CO:H2S=10:1 +200 keV H+

Garozzo et al. 2010, A&A 509, A67

Energetic processing4. Implantation

Effects induced by 30 keV ions bombarding an icy surface

• 103-104 number of bonds (few eV/bond) broken per impinging ion• 103-104 number of bonds (few eV/bond) broken per impinging ion

( number of new species formed)

• 1-100 number of atoms ejected per impinging ion (i.e. sputtering)

IF THE PROJECTILE IS A REACTIVE SPECIES

• 1 number of new species formed which include the projectile

Energetic processingION

(E in keV)TARGETT= 16-150 K

MAJOR PRODUCED SPECIES(In bold those containing theprojectile)

REFERENCES

H (1.5, 30-100)

CO2 CO, H2CO3, CO3, O3

O-H in poly-water

Brucato, Palumbo, Strazzulla.Icarus 125, 135, 1997

SO2 SO3, polySO3, O3 , elemental S Garozzo, et al PlSpSci 56, 1300, 2008

Cn+ (10, 30)

n=1-3

H2O H2O2, CO2Strazzulla, et al. Icarus 164, 163, 2003Lv et al 2012 (submitted)

n=1-3

N (15, 30) H2O H2O2Strazzulla, Leto, Gomis, Satorre, Icarus164, 163, 2003

H2O + CH4 C2H6, CO, CO2, OCN-, HCN Strazzulla, PlSpSci 47, 1371, 1999

O (30) CH4 C2H6, C2H4Palumbo AdvSpRes 20, 1637, 1997

N2 + CH4 C2H6, C2H4, HCN Ottaviano, Palumbo, Strazzulla, ConfProc. SIF 68, 149 , 2000

Sn+ (35-200)

n= 1-11

H2O H2O2

H2SO4 dissolved in H2O

Strazzulla et al. Icarus, 192, 623, 2007

Ding et al. in preparation

The Jovian magnetosphere

Mean Energy Flux (keV cm-2 s-1)

Io 1 x 109

Jupiter’s moons are dipped into the magnetosphere and their surfaces arecontinuously bombarded by energetic ions (mainly H+, Sn+ and On+) acceleratedby Jupiter’s magnetic field:

Io 1 x 109

Europa 6 x 1010

Ganymede 5 x 109

Callisto 2 x 108

Cooper et al., 2001, Icarus 149, 133

Near IR observations made by the NASAGalileo spacecraft showed that:

Other absorption features (*) and their primecandidates are:3.4 m (~2940 cm-1) C-H

On Europa, Callisto and Ganymede H2O ice is dominantEuropa

On Io SO2 ice is dominant

A still open question is to understand if those species arenative from the satellites or are synthesized by exogenicprocesses such as ion implantation.

3.4 m (~2940 cm-1) C-H3.5 “ (~2857 cm-1) H2O2

3.88 “ (~2580 cm-1) S-H, H2CO3**

4.05 “ (~2470 cm-1) SO2

4.25 “ (~2350 cm-1) CO2

4.57 “ (~2190 cm-1) CN* McCord et al.,1997a,b**Hage et al. 1998.

Callisto

Ganymede

Energetic processing4. Implantation

30 keV 13C+ implantation in H2O at 16 K

Strazzulla et al. 2003Lv et al. 2012

Energetic processing5. Residue

Strazzulla et al. 2001

0.5 1.0 1.5 2.0 2.5

0.4

0.6

0.8

1.0

(3)

(1)

Reflecta

nce

(1) Methanol, T = 77 K

after H+

200 keV:

(2) 44 eV/16amu

(3) 103 eV/16amu

(2)

Brunetto et al. 2006

Energetic processing causesdarkening and reddening of

NIR reflectance spectra

0.5 1.0 1.5 2.0 2.50.0

0.2

0.4

0.6

0.8

1.0

(3)

(1)

Re

fle

cta

nce

Wavelength (m)

(1) Benzene, T = 80 K

after H+

200 keV:

(2) 34 eV/16amu

after Ar++

400 keV:

(3) 93 eV/16amu

(2)

0.5 1.0 1.5 2.0 2.5

0.2

0.4

0.6

0.8

1.0

Wavelength (m)

(3)

(1)

Refle

cta

nce

(1) Methane, T = 16 K

after Ar++

400 keV:

(2) 35 eV/16amu

after Ar+

200 keV:

(3) 308 eV/16amu

(2)

0.5 1.0 1.5 2.0 2.5

Wavelength (m)darkening and reddening oforiginal icy samples.

Energetic processing5. Residue

The residue is formedat low temperature

Strazzulla et al. 1991

CO diffusion after ion irradiation

OHdb after ion irradiation Fraction of diffused CO

time (year)0.0 5.0x10

51.0x10

66x10

77x10

7

H2O deposit at 15 K Ion irradiation at 15 K CO deposit at 15 K CO diffusion at 26 K

200 keV H+

time (year)0.0 4.0x10

66.0x10

76.5x10

77.0x10

7

0.0 5.0x1013

5.5x1015

6.0x1015

0.0

0.2

0.4

0.6

0.8

1.0experimental data

fit curve (y=Ae-

)

=4.1310-14

cm2

A=0.98±0.07

norm

aliz

ed

OH

db

ban

dare

a

fluence (200 keV H+

cm-2)

Palumbo 2006

0.0 2.0x1014

4.0x1014

5.5x1015

6.0x1015

0.0

0.2

0.4

0.6

0.8

1.0experimental data

fit curve (y=Ae-

)

=1.1410-14

cm2

A=0.97±0.09

fraction

ofdiffu

se

dC

O

fluence (200 keV H+

cm-2)

Palumbo 2006

Crystallization

Baratta et al. 1994

Baratta et al. 1994

0.6

0.8

1.0

no

rma

lize

dth

ickn

ess

irradiated CO

T = 35 K

CO sublimation

0 200 400 600 800 1000 1200

0.0

0.2

0.4

no

rma

lize

dth

ickn

ess

time (sec)

unirradiated CO

irradiated CO

Sublimation ofCH3OH after

ion irradiation

Palumbo et al. 1999

3rd Annual Meeting

Catania (Italy), 2-5 October 2012

COST Action CM0805The Chemical Cosmos

Key datesFriday 29 June: abstract submission deadlineFriday 20 July: registration deadlineFriday 20 July: registration deadline

http://www.oact.inaf.it/weboac/COST2012/

cuijk mepalumbo lect3-4 - radboud universiteit · 2012. 6. 13. · thermal processing 1. diffusion...

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