g s lodha indus synchrotrons utilization division rrcat, indore
DESCRIPTION
Focused X-Ray Beams : Generation and Applications. G S Lodha Indus Synchrotrons Utilization Division RRCAT, Indore. Advances in Science, Engineering and Technology Colloquium TIFR, August 20, 2010. [email protected]. X-ray Interaction with Matter. source: Spring-8 web site. - PowerPoint PPT PresentationTRANSCRIPT
G S LodhaIndus Synchrotrons Utilization
DivisionRRCAT, Indore
Advances in Science, Engineering and Technology Colloquium TIFR, August 20, 2010
Focused X-Ray Beams :Generation and Applications
X-ray Interaction with Matter
source: Spring-8 web site
Focused X-ray Beams W.C. Roentgen : Refractive index of all materials ≈ unity
Difficult to make an x-ray lens.
With the recent availability of extremely bright x-ray sources (synchrotron storage rings, x-ray free electron lasers, …), R&D efforts towards focusing x-rays to smaller and smaller size have become intense.
At present it is possible to generate focused x-ray beam of <30 nm, using the reflection, diffraction and refraction phenomena in the x-ray region.
Optics for X-ray (~10 keV)
Complex refractive index: n=1-δ+iβ Refraction is small: Re(n)=1-δ with δ=10-6 ….10-5
Focal length: f=R/2 (n-1) = R/2δ Absorption is high: absorption lengths 1μm … 10μm Figure of merit: β/δ = 10-5 (Li,Be) …10-3 (C,Al,Si) …10-1
(Au,Pt,W)
Dilemma smaller f smaller R more flux larger aperture larger R
Why focus x-ray to sub micron size?
X-ray microscopy: Most materials are heterogeneous at length scale of micron to nm (transmission microscopy, scanning microscopy…).
Increased flux: Higher sensitivity due to reduced background.
Small samples or samples in different environment (pressure, temperature, magnetic field …)
General Terminology in X-Ray Optics
Magnification Numerical Aperture Resolution Depth of focus Astigmatism Chromatic Aberration
Ideal focusing lens: Converts plane wave to a spherical wave, with the
conservation of the coherence In-coherent source Geometric Optics Refraction 1/F = (n-1) (1/Do + 1/Di) Coherent source
Wave OpticsRefractionPhase shift along the optical path
For generating x-ray micro/ nano focused beam M~10-2 to 10-4 in synchrotron beamline.
Magnification: M=Di/Do
Numerical Aperture• Measure of light collection power
NA= n Sin θmax
NA ~ 0.5 (D/f)
NA is very closely related to performance of the optics (e.g. depth of focus, diffraction limited resolution, flux etc.). Low NA is one of the major constraint for x-ray optics.
For high photon flux at the focus:High brightness and large numerical
aperture Focusing increases the angular spread. Brightness: B= P/ (ΔAs . ΔΩs) P : radiated power; ΔAs :source area ; ΔΩs : source divergenceThe photon flux at the focus is ~ B. 2 . NA2. η is spot size and η is the efficiency of the optics.
Thus the high photon flux at the focus requires high source brightness and large numerical aperture optics.
Rayleigh’s Criterion: Resolution Limit
Point sources are spatially coherent Mutally incoherent Intensities add Rayleigh criterion (26.5% dip)
Conclusion : With spatially coherent illumination, objects are “just resolavable” when
source: D. Attwood
Resolution improves with smaller λ
Depth of focus
Where is a spot size
source: Xradia
Astigmatism
Source Focus
or
Synchrotron radiation sources
or
Horizontal and vertical focusing are separated at grazing incidence.
fm = (R Sin θ)/2
fs = R/(2Sinθ) Reflection Crossed mirror pair (Kirkpatrick-Baez system)
Chromatic aberration
Reflective Optics: Can focus pink beams using grazing incidence optics. Grazing angles can be higher by using x-ray multilayer reflector, but at the cost of limited energy Diffractive Optics : f ~ E , small NARefractive Optics : f ~ E2
X-ray Micro focussing optics
Reflective optics
Diffractive optics
Refractive optics
X-ray Reflectivity: Single and Multilayer
Single Layer
Total external reflection when θ<θc (a few mrad)
c = √2 = λ√Z
Multilayer
Large θ leads to larger acceptance or shorter mirror length.
Spectral bandwidth ~ a few %
AdvantagesLayer thicknesses can be tailoredCan be deposited on figured surfaces
X-ray Multilayer Optics
Reflective optics
Schwarzschild objective
Wolter microscope
Capillary optics
Kirkpatrick-Baez mirrors
Schwarzschild objective
Near normal incidence with
multilayer coating (126 eV)
N.A. > 0.1
Imaging microscope
source: F. Cerrina (UW-Madison), J. Underwood (LBNL)
Wolter microscope
Use 2 coaxial conical mirrors with hyperbolic and elliptical profile
Imaging microscope Difficult to polish for the
right figures and roughness
Multi- bounce condensing capillary
Easy to make with small opening (submicron) Short working distance (100 μm) Low transmission
Capillary opticsOne-bounce capillary
Large working distance (cm) Compact: may fit into space too small for K-B Nearly 100% transmission N.A. ~ 2-4 mrad (¡Ü 2θc) Difficult to make submicron
spot source: D. Bilderback (Cornell)
Kirkpatrick-Baez mirrors
A horizontal and a vertical mirror arranged to have a common focus
Achromatic: can focus pink beam (but not with multilayer coating)
Can be used to produce ~ round focal spot Very popular for focusing in the 1-10 μmAPS 85x90 nm2 ESRF 45 nm, Spring8 25x30 nm2
(diffraction limit ~ 17 nm)
Diffractive optics
Fresnel zone plates (FZP)
Multilayer Laue Lens (MLL)
Fresnel zone plates (Phase ZP and Amplitude ZP)
Phase For a phase shift of
Efficiency of an amplitude ZP with opaque zones ~ 10%
Efficiency of a phase ZP with π-phase shift ~ 40%
Fabrication Fresnel zone plates
E Anderson, A Liddle, W Chao, D Olynick and B Harteneck (LBNL)
Hard X-ray ZP: recently available
W. Yun (Xradia)
Δr = 24 nm, 300 nm thick, Aspect Ratio = 12.5 (Xradia)
Aspect ratio > 100 is probably difficult to achieve with lithographic zone plates!
Multilayer Laue Lens (MLL)
For high aspect ratio
Aspect ratio > 1000 (Δr = 5-10 nm, 10 μm thick) demonstrated
Source : A. Macrander (APS)
Refractive optics
Compound refractive lens (CRL)
f = R/2N
R radius (~200 m)
N number of lenses (10 …300)
real part of refractive index (10-5 to 10-6)
2R0 800 m -1000 m
d 10 m -50 m
Parabolic profile : No spherical aberration
Small aperture Small focusing strengthStrong absorption E>20keV
Source : Achen Univ., APL 74, 3924 (1999)
What is Synchrotron Radiation?
Synchrotron radiation is emitted from an electron
traveling at almost the speed of light (0.99999999C)
and its path is bent by a magnetic field. It was first
observed in a synchrotron in 1947. Thus the name
"synchrotron radiation".
Generation of Synchrotron Radiation
Synchrotron radiation is emitted at a bending magnet or at an insertion device. Corresponding to the weak and strong magnetic field, there are two types of insertion devices: an undulator and a wiggler.
General Properties of Synchrotron Radiation
Ultra-bright Highly directional Spectrally continuous (Bending Magnet /Wiggler)
or quasi-monochromatic (Undulator) Linearly or circularly polarized Pulsed with controlled intervals Temporally and spatially stable
Synchrotron Radiation Spectrum
Brightness of synchrotron sources
X-ray Sources: Peak Brilliance
America: 18Asia: 25Europe: 22Oceania: 1
IV generation light sources under construction/ planning stage.
Synchrotron Radiation(SR) Sources…
A Typical Synchrotron Facility
(1) Electrons are generated here
(2) Initially accelerated in the LINAC
(3) Then they pass into the booster ring accelerated to c
(4) And are finally transferred into the storage ring
Creating SR light
A typical Synchrotron source
With
BM and ID
Building a Synchrotron Source…
Synchrotron
Magnets
RF systems
LCWBeam physics
Power suppliesSurvey and alignment
Health physicsBeam diagnostics
Cryogenicsetc.
UHV
Controls
Chemical CleaningFabrication and metrology shop
Utilization of the properties of the SR beam: A few examples
Microbeam: Diffractometry, microscopy Pulsed Structure : Time-resolved experiments Energy Tunability: Crystal structure analysis, anomalous dispersionHigh collimation: Various types of imaging techniques with high spatial resolutionLinear / circular polarizion : Magnetic properties of materials.High energy X-ray: High-Q experiments, Compton scattering, Excitation of high-Z atoms High spatial coherence: X-ray phase optics and X-ray interferometry
Application of SR
Life Science
Atomic structure analysis of protein macromolecules
Elucidation of biological functions
Materials Science
Precise electron distribution in inorganic crystals
Structural phase transition
Atomic and electronic structure of advanced materials superconductors, highly correlated electron systems and magnetic substances
Local atomic structure of amorphous solids, liquids and melts
Chemical Science
Dynamic behaviors of catalytic reactions
X-ray photochemical process at surface
Atomic and molecular spectroscopy
Analysis of ultra-trace elements and their chemical states
Archeological studies
Earth and Planetary Science
In situ X-ray observation of phase transformation of earth materials at high pressure and high temperature
Mechanism of earthquakes
Structure of meteorites and interplanetary dusts
Environmental Science
Analysis of toxic heavy atoms contained in bio-materials
Development of novel catalysts for purifying pollutants in exhaust gases
Development of high quality batteries and hydrogen storage alloys
Industrial Application
Characterization of microelectronic devices and nanometer-scale quantum devices
Analysis of chemical composition and chemical state of trace elements
X-ray imaging of materials
Residual stress analysis of industrial products
Pharmaceutical drug design
Medical Application
Application of high spatial resolution imaging techniques to medical diagnosis of cancers
SR Based Research Methods
X-ray Diffraction and Scattering
Spectroscopy and Spectrochemical Analysis
X-ray Imaging
Radiation Effects
Indus building complex
Synchrotron Complex at RRCAT housing Indus-1 and Indus-2
TL-3
TL-1
TL-2
Indus-2, 2.5 GeV SRTrials to store the beam began in
December 2005
Indus-1 (450 MeV, 100 mA)
(Working since 1999)
Booster Synchrotron (700 MeV)
(Started in 1995)Microtron (20 MeV)
(Started in 1992)
Schematic View of Indus Complex
Indus-1 Storage Ring
X-ray absorption and Infra red spectroscopy beamlines under installation
Five beamlines have been operational. Several publications (~50) have resulted from utilization of these beamlines.
Schematic representation of experimental hall
Beamline Range (nm)
Beamline Optics λ/ Δλ Experimental stationPre and Post mirror Monochromator
Reflectivity (RRCAT)
4-100 Au coated Toroidal 1.4 m TGM with three gratings
~400 Reflectometer and time of flight mass spectrometer
Angle Integrated PES (UGC-DAE-CSR)
6-160 Pt coated Toroidal 2.6 m TGM with three gratings
~600 Hemi-spherical analyzer (HSA)
Angle Resolved PES (BARC)
4-100 Pt coated Toroidal 1.4 m TGM with three gratings
~400 Angle resolved HSA electron analyzer
Photo Physics (BARC)
50-250 Au coated Toroidal 1 m Seya-Nomioka ~1000 Absorption cell , sample manipulator
High resolution VUV (BARC)
70-200 Au coated cylindrical 6.65 m off plane Eagle mount spectrometer
~70000 High temperature furnace, absorption cell
Beamlines operational on Indus-1
Reflectivity near absorption edge energies Hydrogen bond braking near absorption edge
energies Interface studies Photo dissociation spectroscopy X-ray multilayer optics and optical response in soft
x-ray region X-ray Telescope Calibration
Recent studies using Indus -1
BM Beamlines BL# Groups
ADXRD (commissioned) BL-12 RRCAT
EDXRD (commissioned) BL-11 BARC
EXAFS (commissioned) BL- 8 BARC
GIMS ( being installed) Bl-13 SINP
PES (being installed) BL-14 BARC
Under Construction
BM MCD/PES BL-1 UGC-DAE-CSR
Imaging BL-4 BARC + UGC-DAE-CSR
ARPES/PEEM BL-6 BARC
White-beam lithography BL-7 RRCAT
Scanning EXAFS BL-9 BARC
XRF-microprobe BL-16 RRCAT
SWAXS BL-18 BARC
Protein Crystallography BL-21 BARC
X-ray diagnostics BL-23 RRCATVisible diagnostics BL-24 RRCATSoft X-ray BL-26 RRCAT
Installedbeing installed/under construction
Indus-2 beamlines
X-ray Multilayer Deposition Laboratory
Reflectivity Beamline Indus-1
0 20 40 60 80 100
10-3
10-2
10-1
100
100 110 120 130 140 150 160
0.0
0.2
0.4
0.6
0.8
Ref
lect
ivity
Incidence angle deg
Ref
lect
ivity
Wavelength A
Normal incidence soft x-ray reflector: Mo/Si multilayer
ASTROSAT :One of the most ambitious space astronomy programme initiated by Space Science Community in India.Payload of soft x-ray imaging telescope (SXT) sensitive to 0.3 to 8 keV is planned.Performance of SXT grazing incidence foil mirrors evaluated using Indus-1 soft x-ray reflectivity beamline
Archana et al Experimental Astronomy (2010) 28:11-23
X-ray calibration: Soft X-ray Telescope
Soft & Deep X-ray Lithography (SDXRL) beamline -BL7
MEMS (Micro-Gears, …)
High aspect ratio micro-structures
Ø Fabrication of Hard x-rays opticsØ Small periodicity gratings Ø Micro Electro Mechanical Systems (MEMS)Ø Photonic band gap crystals (for visible radiation)Ø Quantum wires and quantum dots devices (high density pattering over large areas)Ø Fabrication of high density hetrostructures for nano devices
SDXRL beamline - Applications
Zone Plate
Primary slits
X-ray mirrors with manipulators
Installed beamline inside hutch
X-ray Scanner
SDXRL beamline – Present Status
BL16
Beamline Front EndBeamline optics
Pre-DCM section
DCM
Front end exit
Beam transport pipes and vacuum components
KB mirror
X-ray Microprobe beamline
Beamline optics Post-DCM section
Optics table Beam
transport pipes and vacuum components
DCM
Road Ahead….• A modest start has been done at RRCAT with
the availability of synchrotron radiation sources Indus-1 and Indus-2. These sources are being operated on a round the clock basis, week after week.
• Few x-ray beamlines have become operational, with many more in implementation stage.
• These are national science facilities. Users from various fields are welcome to plan research using these facilities, which will significantly help us to improve the performance further. It will be our endeavor to support all users of this national facility.
67
All are welcome to Indus SR Facility
Acknowledgements:
X-ray Diffraction and ScatteringResearch Methods Typical Examples of Research SubjectsMacromolecular crystallography ( I-2)
Atomic structure and function of proteins.
X-ray diffraction under extreme conditions (I-2)
Structural phase transition at high pressure / high or low temperature
X-ray powder diffraction (I-2)
Precise electron distribution in inorganic crystals
Surface diffraction (I-2) Atomic structure of surfaces and interfaces. Phase transition, melting, roughening, morphology and catalytic reactions on surfaces
Small angle scattering (I-2) Shape of protein molecules and biopolymers. Dynamics of muscle fibers
X-ray magnetic scattering Magnetic structure. Bulk and surface magnetic properties
X-ray Optics X-ray interferometry. Coherent X-ray optics. X-ray quantum optics
Spectroscopy and Spectrochemical Analysis
Research Methods Typical Examples of Research SubjectsPhotoelectron spectroscopy (I-1)
Electronic structure of advanced materials such as superconductors, magnetic substances, and highly correlated electron systems.
Atomic and molecular spectroscopy (I-1)
Photoionization spectra, photoabsorption spectra and photoelectron spectra of neutral , atoms and simple molecules. Spectra of multicharged ions.
X-ray fluorescence spectroscopy (I-2)
Ultra-trace element analysis. Chemical states of trace elements. Archeological and geological studies.
X-ray absorption fine structure (I-2)
Atomic structure and electronic state around a specific atom in amorphous materials, thin films, catalysts, metal proteins and liquids.
X-ray magnetic circular dichroism (I-2)
Magnetic properties of solids, thin films and surfaces. Orbital and spin magnetic moments.
Infrared spectroscopy (I-2) Infrared microspectroscopy. Infrared reflection and absorption spectroscopy.
X-ray inelastic scattering Electronic excitation. Electron correlations in the ground state. Phonon excitation.
X-ray Imaging
Research Methods Typical Examples of Research Subjects
Refraction-contrast imaging (I-2)
lmaging of low absorbing specimens.
X-ray fluorescence microscopy (I-2)
Imaging of trace elemental distribution with a scanning X-ray microprobe.
X-ray microscopy (I-2) Imaging of materials by magnifying with microfocusing elements.
X-ray topography (I-2) Static and dynamic processes of crystal growth, phase transition and plastic deformation in crystals. Crystal lattice imperfections.
Photoelectron emission microscopy (I-2)
Element-specific surface morphology. Chemical reaction at surface. Magnetic domains.
Radiation Effects
Research Methods Typical Examples of Research SubjectsMaterial processing (I-2) Soft X-ray CVD. Microfabrication.Radiation biology (I-2) Radiation damage of biological substances.
-10 0 10 20 30 40 50 60 70 801E-4
1E-3
0.01
0.1
1
Refle
ctivit
y
Incidence angle deg
Measured Fit
N=120 layersTop SiO2 20.7A: 6.7A: 2.78e-2Si 72.0A; 7.1; 4.22e-3; 1.94e-3Mo 31.0A; 7.0 ; 7.99e-2; 8.66e-3;SubS 5.0ABeam polarization 80%
wavelength 138A
Mo/Si soft x-ray Polarizer multilayer