Post on 14-Jun-2020
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European Synchrotron Radiation Facility
Jean SUSINI
COHERENT X-RAYS AND THEIR APPLICATIONSA series of tutorial–level lectures edited by Malcolm Howells
Lecture 6 - 9th June 2008
Coherence activities at the ESRF:
Scanning (Transmission) X-ray Microscopy
STXM ���� SXM
A Practical Approach
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Scanning X-ray microscope arrangements
XPSanalyser
� Soft X-rays (δ ~ 40nm)
Scanning Photo-Emission Microprobe
� Hard X-rays (δ ~ 80nm)
X-ray Fluorescence Microprobe
Energy Dispersivedetector
Crystal spectrometer
� Soft- X-rays (δ ~ 20nm)
� Hard X-rays (δ ~ 80nm)
Scanning Transmission X-ray Microscope
X-raydetector
λλλλ
λλλλ
λλλλ
• Detection of signals arising from interaction of small probe with sample
• Sample scanned through beam to build ‘image’
pixel by pixel
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Synchrotron based micro-probe techniques
X-Ray Fluorescence
X-ray spectroscopy
X-rayDiffraction & scattering
InfraredFTIR-spectroscopy
• Composition• Quantification
• Trace element mapping
• Short range structure
• Electronic structure
• Oxidation/speciation mapping• Molecular groups & structure
• High S/N for spectroscopy• Functional group mapping
• Long range structure• Crystal orientation mapping
• Stress/strain/texture mapping
Phase contrast X-ray imaging
• 2D/3D Morphology• High resolution• Density mapping
ID11, ID13, ID22
ID21, ID22, ID24
ID21
ID21, ID22
ID13, ID21, ID22
ESRF instruments
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Synchrotron based hard X-ray microprobe
Photodiode
Undulator
Crystal monochromator
X-ray lens
Aperture
Sampleraster scanned
Fluorescence detector
CCDDiffraction
CCDAlignment & imaging
• Spatial resolution : 0.05-1µm
• Spectral resolution : 10 -2 > ∆E/E > 10-4
• Averaged flux : 10 10 – 1013photons/s/µm 2
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Synchrotron micro-probes
focus
Low ββββz25x930µm2 - 17x29µrad2
High ββββz25x135µm2 - 17x208µrad2
(Secondary) source 50-250m
< 50x50nm2
Diffractive lenses Refractive lenses
X-ray waveguides X-ray reflectors
• Resolution determined by probe size and overall stability
• Size of the probe is a convolution of the geometric image of the source and the point spread function of the lens
• Diffraction limited vs aberration limited?
• Coherent illumination required for diffraction-limited resolution but images are not coherent.
• SXMs are coherent (brightness) experiments
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Diffraction limited focusing
qpf
111 +=p
qsG ×Σ=
αsinnNA=
Geometrical demagnification:
Diffraction limited focusing ifπλθ4
=×Σ
Thin lens equation
Numerical aperture
NACsDL
λ= where C=0.61 for a circular aperture
p q
Σ sααααθθθθ
Central Airy disk
NAd
λ22.1=
for circular lens
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
A trade-off
p q
Σ sααααθθθθ
Central Airy disk
NAd
λ22.1=
for circular lens
Optical aberrations often limit resolution before diffraction limit is reached
p
qsG ×Σ=
Geometrical demagnification Coherent illumination
αλ
sin22.1=DLs
• Source size (horiz. vs. vert.)
• Distance source-optics
• Working distance
• Working distance
• Lens aperture
• Beam divergence
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Ideal focusing of a point source
� Focusing: equal optical paths source-to-focus
� Ellipse definition: p + q = constant
Courtesy C. Morawe (Optics Group)
pq
5
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
A fundamental limit: “Liouville’s theorem”
1 - The phase-space density of photons cannot be increased.
2 - In fact, because of absorption and finite efficiency of the optical elements, the phase-space density decreases.
3 - Implications for diffraction experiments.
The emittance εεεεsize x divergence
is constant
ε ε ε ε = ∆= ∆= ∆= ∆i’ x ∆∆∆∆i = const
• Focussing : Size and divergence
• Collimating : Size and divergence
Beam divergence∆x’, ∆y’, ∆z’
Beam size∆x, ∆y, ∆z
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Undulator beam and spatial modes
From lecture 4, M. Howells
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Some source parameters
ESRF highlights 2007 p.121
High beta section (even IDs)
• Size H : 415.0µm
• Div. V : 2.9µrad
• Size V : 8.6µm
• Div. H : 10.3µrad
Electron beam parameters (RMS)
Low beta section (odd IDs)
• Size H : 51.0µm
• Div. V : 2.9µrad
• Size V : 8.6µm
• Div. H : 108.0µrad
Photon source parameters (RMS)
High beta section
• Size H : 415.0µm
• Div. V ~ 13-5µrad (5-40keV)
• Size V : 8.6µm
• Div. H ~ 16-11µrad (5-40keV)
Low beta section )
• Size H : 51.0µm
• Div. V ~ 13-5µrad (5-40keV)
• Size V : 8.6µm
• Div. H : 108.0µrad
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Some beam parameters
0
500
1000
1500
2000
2500
5 10 15 20 25 30 35 40
0
2
4
6
8
10
12
14
16
18
20
High ββββHorizontal
Low ββββHorizontal
Low-High ββββVertical
Energy (keV)
Num
ber of modes
Vertical
Num
ber
of m
odes
Hor
izon
tal
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
5 10 15 20 25 30 35 40
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
1.80
Energy (keV)
Bea
m s
ize
(mm
)H
oriz
onta
l
Beam
size (mm
)V
erticval
High ββββHorizontal
Low-High ββββVertical
Low ββββHorizontal
FWHM Beam size @ 50m from the source
High beta sources provide a slightly more
“coherent” beam
A coherent experiment uses only one mode!!
What about the wasted modes?
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Source demagnification : Scheme 1
• Requires a small pinhole (difficult to produce for hard X-ray?, heat load?, ….)
• Compromises the energy tunability ?
• Compact and stable instrument
• Overfilling of the slits makes the beamline less sensitive to drifts and vibrations
• Optical optimization is possible
• The secondary slit can be used to clean-up the beam (speckles from upstream components)
• Trade-off flux vs. resolution is tunable
A “ short” beamline with a secondary source
20x100nm225 x 900mm2
30m 1m 30m 0.1m
M1=1/30
30x30mm2
M2=1/300
See also lecture 3 (A. Snigirev)
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Source demagnification : Scheme 2
• Exploits the source size (low β or apertured high β )
• Allows long working distance
• Preserves the coherence
• Preserves the energy tunability (spectroscopy)
• Preserves the vertical divergence tunability (diffraction)
• Overall stability
• Flux losses or large aperture optics
• Cost
Long beamline with a direct source demagnification
150m
25x150mm2
M=1/1500
20x100nm2
0.1m
See also lecture 3 (A. Snigirev)
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
High energy = very grazing incidence
+=
+=
qp
qpR
qp
qpR
is
im
θ
θ
sin2
sin
2
Radii of curvature
Source
Focus
• Small θ −> Long mirror (> 1m) or small NA• Off-axis geometry
• Aberrations (spherical aberration, astigmatism, figure errors)
θ < θc ~ 10mrad2θms RR ≈≈≈
kmR
mmR
m
s
]/[ 3][][
83.19cmgcc keVmrad
E ρθ =
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Mirror shapes : z = ααααy2(1+ββββy+γγγγy2), Rc ~ 1/2α/2α/2α/2α
Source Focus
pqθθθθ
• Ellipsoidal : point-to-point focussing
−+=
−=
+=
q
p
ppq
q
p
p
q
p
p
e
e
e
116
cos5
4
1
12
cos
14
sin
2
2 θγ
θβ
θα
J. Susini, Optical Engineering, 34 (2) (1995)
“ideal” ellipse are extremely difficult to manufactured
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Kirkpatrick-Baez geometry
Principle : perpendicular meridian planesP. Kirkpatrick and A.V. Baez,
“Formation of optical images with X-rays”J. Opt. Soc. Amer., 38, (1948)
Kirkpatrick-Baez mirror pair
Source
FocusSpherical aberrations ~ 1/L 2
Multilayer coating : Bragg angle ���� shorter mirror or/and larger aperture
L
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Kirkpatrick-Baez system at the ESRF
ApertureV X H (µm)
Focus SizeFWHM (nm)
FluxPh/s @ 90mA
200 X 50 92 X 87 5 10 10
400 X 100 70 X 74 2 10 11
600 X 160 90 X 70 4.5 10 11
microfocus on ID19 ( 20.5 keV)
ESRF: 40nm
O. Hignette et al., AIP Conf. Proc. 879 (2007)
Spring8: 25nm
H. Minura et al., APL 90 (2007)
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Fresnel Lenses – Zone Plates
Augustin-Jean Fresnel1788-1827
Diffractive X-ray Lenses
Circular transmissive diffraction gratings with radially decreasing line width giving focusing effect
Alternate ‘zones’ modify phase/amplitude of incident wavefront:
for material of thickness, t, wavelength, λ, refractive index 1-δ-iβ,
phase shift, ∆φ, is:
λδπφ t2=∆
For X-rays:
Baez (1952), Schmahl (1969), Kirz (1971), Niemann (1974)
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Fresnel zone plates: a Gabor hologram of a point object
Planar wavefrontHologram (Fresnel Zones)
Reconstructionby
coherent illumination
focus
Diffraction limit ( δ=1.22∆rN)
• requires coherent illumination
• λλλλ /∆λλλλ > N
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Fresnel Zone Plates
D
∆∆∆∆rNt
� Resolution:m
rNm
∆= 22.1δ
� Focal length:λm
rDf N
m
∆=
� Depth of focus:λm
rDOF N
24∆±=
• m=1
• ∆rN=50nm
• D=100µm
8µm @500eV
160µm@10keV
2mm @500eV
40mm@10keV
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Soft X-ray zone- plates
E. Anderson, Center for X-Ray Optics, LBNL, USA
• ∆∆∆∆rN = 25 nm
• D = 63 µm
• N = 618 zones
• f = 650 µm
• NA = 0.05 @ λ = 2.4 nm
• ∆rN = 15 nmW. Chao et al., Nature 435 (2005)
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Zone plate aspect ratiostructure height, t, critical for efficiency, ∆∆∆∆rN for resolution
Aspect ratio for ∆∆∆∆rN=50nm
Nickel25%
12 : 1
2.0 keV
Tantalum32%
28 : 1
8.0 keV
Nickel24%6 : 1
0.5 keV
Practical limit for small ∆∆∆∆rN is ~ 10-15:1
∆∆∆∆rN
t
Material t (µm) ε (%)E=0.5keVGe 0.28 16Ni 0.25 24
E=2.0keVNi 0.60 25Au 0.45 24
E=8.0keVTa 1.70 32W 1.50 33
t
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
( )
2
2
sin1
≈p
p
mpm π
πε
ε1(2) = 40.5%
ε1(3) = 68.5%
ε1(4) = 81.2%
Fresnel zone-plates: several strategies
Amplitude
Phase
Blazed
Ideal 3-levelapproximation
X-ray opaque material
X-ray phase shifting material
• Amplitude : Opaque zones (K→ ∞)
• Phase : weak absorbing and phase reversal zone (Κ→0 and Φ = π)
ε1 ~ 10% and ε3 ~ 1%
ε1 ~ 40 %
( )Φ−+= ΚΦ−ΚΦ− cos211 2
22ee
mm πε
• Grating with equal lines and spaces
m = ±1, ±3, ±5,….λ
δπδβ t
K2
and =Φ=
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Blazed zone plate: 3 level lens
E. di Fabrizio et al., Nature 401 (1999)
• material : Nickel
• diameter : 150µm
• ∆RN : 150nm
7 keV : ε ~ 57%
0
20
40
60
80
100
5 5.5 6 6.5 7 7.5 8 8.5 9
Effi
cien
cy (
%)
Energy (keV)
calculated (ideal)
calculated (with fabrication errors)
measured
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Rejection of the unwanted diffraction orders
m = 1
ORDER SELECTING APERTURE
FIRST ORDER FOCUS
CENTRAL STOP
Zone-plate based SXM = Central stop + ZP + OSA
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
SXM – ID21 – Old version
DET
SAM
OSA
ZP
EW
PZTX-rays
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Multilayer Laue Lenses
substrate
Varied line-spacing grating
Depth-graded multilayerson flat Si substrate
• Deposit varied line-spacing grating on flat substrate(thinnest structures first)
• Section to 5-20 µm thickness (high aspect ratio structure)
• Assemble two into a single device (MLL)
H. C. Kang et al., Phys. Rev. Lett. 96 (2006)
15
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Tentative of comparison
• Resolution ++++ +++ +++
• Achromaticity -(-) +++(+) --(-)
• Efficiency + +++(+) ++
• Imaging (MTF) ++++ ++ +++
Zones plates Refractive lenses
Kirkpatrick-Baez mirror pair
Mirrors
Energy
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray Fluorescence: a brief reminder
� Element specific
� Co-localization
� Quantification
X-rayKen
ergy
continuum
ML
Photo-electroncontinuum
ML
K
KααααKββββ
Eexc
Energy dispersivedetector
energy
Inte
nsity
16
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
XRF on synchrotron beamline = low detection limit
monochromaticbeam
( 10-5< ∆E/E < 10-2)
High flux
45°
45°
EDS
Horizontal Linearpolarization
Broad spectrumBright
coherent
0.01
0.1
1
10
100
1000
104
105
10 15 20 25 30 35 40
Atomic number Z
MDL (ppm) on NIST 1577 (10sec)
PS
Cl
KCa
Mn
Fe
CuZn Se Br
10-18 g in a cell
• Low background
• Tunable energy (XANES)
Only a few degrees collection angle!
Detector developmentsDwell time < 100ms
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
µ-XRF in Trichomes of Arabidopsis Thaliana
P
70 µm
S Cd K Ca
Eex: 5.8 keV, probe size: 0.3x0.2 µm2, dwell time: 800 ms/pixel.
M.P. Isaure et al ., Biochimie , 88, 2006
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Fluorescence tomography (3D-µXRF)
Pixel- by-pixel acquisition Sinogram(s) 2D-Slice or 3D-Volume
2D X-rayFocusing device
EDS
Sample
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Fluorescence tomography (3D-µXRF)
Pixel- by-pixel acquisition Sinogram(s) 2D-Slice or 3D-Volume
� The reconstruction problem is far more difficult compared to
transmission tomography
� self absorption corrections
� µ(Ea, x) is a priori unknown
� weak fluorescence signal for light elements
18
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Fluorescence tomography (3D-µXRF)
Pixel- by-pixel acquisition Sinogram(s)
Algorithmic solution:Optimal estimation of attenuation maps by combination of transmission, fluorescence and Compton tomographies
• B. Golosio et al., J. Appl. Phys. 94(1) (2003)
2D-Slice or 3D-Volume
Geometrical solution:Collimation of the detection angle to define a voxel: confocal geometry
• B. L. Vincze et al., Anal.Chem., 76(22) (2004)
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Combining several signals
Absorption tomography (σσσσphoto ~Z4)�Absorption coefficient maps
Compton tomography (σσσσCompton ~Z)�Electronic density maps
Fluorescence tomography�Elemental composition maps
B. Golosio et al., J. Appl. Phys. 94 (1) (2003)
EDS
EDS
Integration of the informationAbsorption + Compton + Fluorescence
QUANTIFICATION
B. Golosio et al , APL 84 (2004)
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Single Fly Ash Particle
Combined Tomographies
Transmission Tomography
Rubidium
Iron
Manganese
B. Golosio et al , Applied Phys. Letters , 84 (2004)
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
XRF Tomography – “confocal geometry”
Polycapillary
Coincidingfocii
FocussedX-ray beam
XRFdetector
� Spatial resolution: 5-10µm
L. Vincze et al., Anal.Chem. 76 (22) (2004)
Si(Li) detector
I0
Optical microscope
90°
Focusing lensSample
CCDAlignment
& imaging
ESRF - ID18F
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
From 3D-confocal XRF to quantification
unusual high Ca concentration
“Ca-rich lithology in the Earth's deep (> 300 km)
convecting mantle ”
Quantification using NIST SRM 613
CaMn
Fe
PbHf Th
SrZr
Y
Phase 1 (Sr)
Phase 2 (Y,Zr)
Zr
YScatter peaks
Ca: 260 ppm, Sr: 1.2 ppm, Zr: 1.1 ppm
Detection limits (LT=100 s):
B. Vekemans et al., JAAS. 19(10) (2004) F.E. Brenker et al., EPSL 236 (2005)
Y, Zr Sr
Th
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray Absorption Near Edge Spectroscopy (XANES)
• Local site symmetry
• Oxidation state
• Orbital occupancy
Energy
Nor
m. f
luo
yiel
d or
-al
ogI/I
0Continuumstates
Rydbergstates
σσσσ
σσσσ∗∗∗∗
ππππππππ∗∗∗∗
1sX-ray
Electronic transitions to bound states, nearly bond states or continuum
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Chromium chemical mapping in cells
0
1(a.u.)
Potassium Cr (total)
Cr(VI)
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5.96 5.98 6 6.02 6.04 6.06 6.08 6.1
CrCl3PbCrO4
Tra
nsm
itte
d in
ten
sity
(a
.u.)
Energy (keV)
R. Ortega et al. , Chem. Res. Toxicol. , 5, (2005)
Micrograph
10 µm
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Absorption and Phase contrasts
Absorption contrast
~ 1 / E3
Phase contrast
~ 1 / E
Refractive index n for X-ray wavelengths: n ~ 0.999999
n = 1 - δδδδ + i ββββ
phaseamplitude
Pha
se v
sam
plitu
de
0.1
1
10
100
1000
0.1 1 10 100
Hard X-rays
Soft X-rays
Energy (keV)
(δδδδ/ββββ) = f(E) for Al
See lecture 5 - P. Cloetens
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray microscopy techniques using phase shifting
Schmahl et.al(1993)
Zernike phase contrastwith phase shifting annular plate in back-Fourier plane of imaging objective
soft X-rays & keV photons)
Bonse / Hart(1968)
X-ray interferometerbased on double crystal in Laue geometry
keV photons
Morrison et.al(1996)
Differential phase contrastusing a quadrant detector similar to SEM
soft X-rays & keV photons
Polack / Joyeux(1995)
Kaulich / Wilhein(2002)
Differential phase contrastusing Young type slits or a Fresnel bi-mirror
Using 2 zone-plates
soft X-rays (keV photons)
SXM TXM
√√√√
√√√√
√√√√
√√√√
x
x
x x
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Phase contrast in SXM ?
Phase gradientsdue to material inhomogeneities or thickness variations
Intensity variation ?
Differential Interference Contrast(DIC)
Phase effects+
interference fringes =
intensity variation
Differential Phase Contrast(DPC)
Beam deflection+
Configured detector =
intensity variation
2 options
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
DPC: SXM and configured detectorsPhase gradients due to material inhomogeneities or thickness variations
cause a deflection of the microprobe beam
� A single element detector would record the intensity but no information on the degree of deflection � Absorption only
� If the detector is split into several pixels, the beam deflection leads to intensity variation can detected� Phase information can be extracted.
See also Lecture 4 (M. Howells)
• STXM and TXM imaging modes can produce equivalent image contrast
• The roles of source and detector can be interchanged• STXM mode allows some imaging conditions to be realized more easily than in TXM mode,
• … and vice versa !
Reciprocity Principle
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
DPC and fast-readout CCD array detector
CVD DiamondID21
3.3keV100nm pixel size
5 µm
R(k)=1 R(k)=k x R(k)=k y
• 80x80pixels
• Spreads signal across many detector elements
• Extends the dynamic range for which photon counting is possible.
• Allows flexible choice of imaging modes (with simultaneous absorption, phase and dark field contrast)
G.R. Morrison et al., Journal de Physique IV 104 (2002)
W. Eaton et al., AIP Proceedings 507 ( 2000)
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ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Configured segmented detector
• M. Feser et al., NIM A. 565 (2006)
• B. Hornberger et al. Ultramicroscopy 107(8) (2007)
• M.D. de Jonge et al., Microsc Microanal 13(2) (2007)
(4+5)-(6+7)Σ Σ Σ Σ segments
Ge siemens star525eV
X1A microscope NSLS
Diatom10keV
Beamline 2-ID-E APS
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Differential Interference Contrast (DIC)
Visible light microscopy
G. Nomarski, 1960
The image of DIC microscopes is formed from the interference of two mutually coherent waves with lateral displacements (shear) of the order of the minimum size of the imaged structure and are phase-shifted relative to each other
• Two plane polarizers are involved, one before the condenser and one after the objective.
• Birefringent prisms act on the plane polarized light first to split the beam in two, and later to recombine the two beams.
The intensity distribution in measured DIC images is given by
a non linear function of the spatial gradient of a specimen’s
optical path length distribution along the direction of shear
25
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Differential Interference Contrast (DIC)
Visible light microscopy X-ray microscopy
fZP1 - fZP2
G. Nomarski, 1960
• T. Wilhein et al., Appl. Phys. Lett . 78(14), (2001)
• T. Wilhein et al., Optics Communication 193, (2001)
• B. Kaulich et al., J Opt Soc Am A 19(4), (2002)
• B. Kaulich et al., Optics Express , 10(20) (2002)
• E. Di Fabrizio et al., Optics Express , 11(19) (2003)
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray Differential Interference Contrast (X-DIC)
∆s < δ
∆f < D.O.F.
� Shear of wave front division or distance of Airy disks in focal plane is smaller than optical resolution (“differential”)
λ=0.3nm
ffffZP1 - ffffZP2
• Distance ∆∆∆∆ffff of both ZPs smaller than depth of field
• Displacement ∆∆∆∆s smaller than resolution δδδδ
Bright field
X-DIC
26
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray Differential Interference Contrast (DIC)
10µm
Absorption
-0.01
-0.005
0
0.005
0 5 10 15
microns
C~ 1%
-0.3
-0.2
-0.1
0
0.1
0.2
0 5 10 15 20
microns
10µm
DIC
C > 28%
PMMA test objectID21
E=5keV
B. Kaulich et al., J Opt Soc Am A 19(4), (2002)
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray Differential Interference Contrast (X-DIC)
Development of multi-spot zone plates by reconstruction of the hologram of a plane wave and several spherical waves
(TASC-INFM, Trieste, Italy)
E. di Fabrizio et al., Optics Express , 11(19) (2003)
27
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-ray Differential Interference Contrast (X-DIC)
• E = 5.8keV (λλλλ=2.1Å)
• Dwell time: 50 ms/px
• Probe size: 0.6x0.7µm 2
20 µm
Absorption X-DIC (phase)
Cell membranes of maize plant cells
unpublished
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
X-DIC+XRF microscopies = Quantification?
Arabidopsisthaliana
X-DIC
Density+thickness map
µ-XRF
Intensity maps
5µm
quantification
high
low
28
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Multi-keV X-ray microscopy
� Contrast mechanisms
• Phase contrast
• X-ray fluorescence
• Micro-spectroscopy (XANES)
Lower exposure dose
Trace element detectionQuantitative XRF analysis
Chemical state specificity
� Geometry
• Spatial res.: 1000nm → 30nm
• Field of view: variable
• Depth of field > 10µm
• Working distance > 20mmSample environment (cryo)In-situ
Multi-scale (meso-scale)
Tomography
� Sample
• Hydrated-frozen
• Thick
• Minimum preparation
Cryo is mandatory
No labeling
No sectioning
ESRF Lecture Series on Coherent X-rays and their Applications, Lecture 6 - Jean Susini
Needs for a multi- modal approach
Abundance Quality%
ppmppb structural
chemicalelemental
Scale
mm
µm
nm
Multi-modal analysis
Multi-variate data processing
In-situ
Quantification
3D
Detectors
Detection geometry
Source and optics