Indus Synchrotrons Utilization Division RRCAT Indore Advances in Science Engineering and Technology Colloquium TIFR August 20 2010 lodharrcatgovin Focused XRay Beams Generation and Applications ID: 418358
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Slide1
G S Lodha
Indus Synchrotrons Utilization Division
RRCAT, Indore
Advances in Science, Engineering and Technology Colloquium TIFR, August 20, 2010
lodha@rrcat.gov.in
Focused X-Ray
Beams :
Generation
and ApplicationsSlide2
X-ray Interaction with Matter
source:
Spring-8 web siteSlide3
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. Slide4
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/2
δ
Absorption is high: absorption lengths 1
μm … 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 RSlide5
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 …)Slide6
General Terminology in
X-Ray Optics
Magnification Numerical Aperture
Resolution Depth of focus Astigmatism
Chromatic Aberration Slide7
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/D
o + 1/Di)Coherent source
Wave Optics Refraction
Phase shift along the optical path
For generating x-ray micro/
nano
focused beam M~10
-2
to 10
-4 in synchrotron beamline
.
Magnification: M=D
i
/DoSlide8
Numerical Aperture
Measure of light collection power
NA= n Sin θmaxNA ~ 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.Slide9
For high photon flux at the focus:
High brightness and large numerical aperture
Focusing increases the angular spread. Brightness: B= P/ (Δ
As . ΔΩs) P : radiated power; Δ
As :source area ; ΔΩ
s : source divergence
The photon flux at the focus is ~ B
.
2
. NA
2. 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.Slide10
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 Slide11
Resolution improves with smaller
λSlide12
Depth of focus
Where
is a spot size
source
:
Xradia
Slide13
Astigmatism
Source
Focus
or
Synchrotron radiation sources
or
Horizontal and
vertical focusing
are separated at
grazing incidence
.
f
m
=
(R Sin
θ)
/2
f
s
= R/(2Sin
θ
)
Reflection Crossed mirror pair (Kirkpatrick-Baez system)Slide14
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 Slide15
X-ray
Micro
focussing optics Reflective optics Diffractive optics
Refractive opticsSlide16
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 %Slide17
Advantages
Layer thicknesses can be tailored
Can be deposited on figured surfaces
X-ray Multilayer OpticsSlide18
Reflective optics
Schwarzschild objective Wolter microscope Capillary optics
Kirkpatrick-Baez mirrorsSlide19
Schwarzschild objective
Near normal incidence with multilayer coating (126 eV)
N.A. > 0.1
Imaging microscope
source
: F.
Cerrina
(UW-Madison), J. Underwood (LBNL
)Slide20
Wolter
microscope
Use 2 coaxial conical mirrors with hyperbolic and elliptical profile
Imaging microscope
Difficult to polish for the right figures
and roughnessSlide21
Multi- bounce condensing capillary
Easy to make with small opening (submicron)
Short working distance (100 μm) Low transmission
Capillary optics
One-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)Slide22
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
μm
APS
85x90 nm
2
ESRF 45 nm, Spring8 25x30 nm2
(diffraction limit ~ 17 nm)Slide23
Diffractive optics
Fresnel zone plates (FZP) Multilayer Laue Lens (MLL)Slide24
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%Slide25
Fabrication Fresnel zone plates
E Anderson, A
Liddle
, W Chao, D Olynick and B Harteneck
(LBNL)Slide26
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!Slide27
Multilayer Laue Lens (MLL)
For high aspect ratio
Aspect ratio > 1000 (Δ
r = 5-10 nm, 10 μm thick) demonstrated
Source : A
.
Macrander
(APS)Slide28
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
mParabolic profile : No spherical aberrationSmall aperture Small focusing strengthStrong absorption E>20keVSource : Achen Univ., APL 74, 3924 (1999)Slide29
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".Slide30
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.Slide31
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 stableSlide32
Synchrotron Radiation SpectrumSlide33
Brightness of synchrotron sourcesSlide34
X-ray Sources: Peak BrillianceSlide35
America: 18
Asia: 25
Europe: 22Oceania: 1IV generation light sources under construction/ planning stage.
Synchrotron
Radiation(SR) Sources…Slide36
A Typical Synchrotron FacilitySlide37
(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 IDSlide38
Building a Synchrotron Source…
Synchrotron
Magnets
RF systemsLCW
Beam physics
Power supplies
Survey and alignment
Health physics
Beam diagnostics
Cryogenics
etc.
UHV
Controls
Chemical Cleaning
Fabrication and metrology shopSlide39
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 dispersion
High collimation:
Various types of imaging techniques with high spatial resolution
Linear / 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
Slide40
Application of SRSlide41
Life Science
Atomic structure analysis of protein macromolecules Elucidation of biological functionsSlide42
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 meltsSlide43
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 studiesSlide44
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 dustsSlide45
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 alloysSlide46
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 designSlide47
Medical Application
Application of high spatial resolution imaging techniques to medical diagnosis of cancersSlide48
SR Based Research Methods
X-ray Diffraction and Scattering Spectroscopy and
Spectrochemical Analysis X-ray Imaging
Radiation EffectsSlide49
Indus building complexSlide50
Synchrotron Complex at RRCAT housing Indus-1 and Indus-2Slide51
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 ComplexSlide52
Indus-1 Storage RingSlide53
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 hallSlide54
Beamline
Range (nm)
Beamline
Optics
λ/
Δλ
Experimental station
Pre 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-1Slide55
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 -1Slide56
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
RRCAT
Visible diagnostics
BL-24
RRCAT
Soft X-ray
BL-26
RRCAT
Installed
being installed/
under construction
Indus-2
beamlinesSlide57
X-ray Multilayer
Deposition LaboratorySlide58
Reflectivity
Beamline
Indus-1Slide59
Normal incidence soft x-ray reflector: Mo/Si multilayerSlide60
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 TelescopeSlide61
Soft & Deep X-ray Lithography (SDXRL)
beamline
-BL7Slide62
MEMS (Micro-Gears, …)
High aspect ratio micro-structures
Ø
Fabrication of Hard x-rays optics
Ø
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
- ApplicationsZone PlateSlide63
Primary slits
X-ray mirrors with manipulators
Installed beamline inside hutch
X-ray Scanner
SDXRL
beamline
– Present StatusSlide64
BL16
Beamline Front End
Beamline opticsPre-DCM section
DCM
Front end
exit
Beam transport pipes and vacuum components
KB mirrorSlide65
X-ray Microprobe
beamline
Beamline opticsPost-DCM section
Optics table
Beam transport pipes and vacuum components
DCM
Slide66
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.Slide67
67
Thank you
All are welcome to Indus SR FacilitySlide68
Acknowledgements:Slide69
X-ray Diffraction and Scattering
Research 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 fibersX-ray magnetic scattering Magnetic structure. Bulk and surface magnetic propertiesX-ray OpticsX-ray interferometry
. Coherent X-ray optics. X-ray quantum opticsSlide70
Spectroscopy and
Spectrochemical
AnalysisResearch MethodsTypical
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. Slide71
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.Slide72
Radiation Effects
Research Methods
Typical Examples of Research Subjects
Material processing (I-2)Soft X-ray CVD.
Microfabrication.
Radiation biology
(I-2)
Radiation damage of biological substances. Slide73
Mo/Si soft x-ray Polarizer multilayerSlide74Slide75Slide76