Overview of Synchrotron Radiation
Cheiron School 2008, SPring-8
Keng Liang
September 29, 2008

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Light Source: Sun

The Sun appears to have been active for 4.6 billion years andhas enough fuel to go on for another five billion years or so.
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Light: wave or particle
Isaac Newton, 1642-1727+ The prism: Energy Analyzer (energy resolution)+ The eye: Detector (sensitivity)+ Wave: described by wave length, phase, amplitude+ Matter: optical index of reflection
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ze/m = 1.76*108 c/g

J.J.Thomson was awarded the 1906 Nobel Prize in Physics forthe discovery of the electron and his work on the conduction ofelectricity in gases.

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Year 1895

Wilhelm Röntgen produced and detected electromagnetic radiation
in a wavelength range known as x-rays today; this achievement earned
him the first Nobel Prize in Physics in 1901.
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v=

2 Ek
me

沒考慮相對論所算出的電子速度

電子速度 [倍光速 c]

1.2

1.0

0.8

0.6

實驗室看到的
電子速度
⎞

0.4

⎛
Ek
⎜ 1+
⎟
2me c 2 ⎟2 Ek ⎜v=m e ⎜⎜ 1 + Ek ⎟⎟0.2⎜
me c 2 ⎟
⎝
⎠

0.0
0.0

0.5

1.0

1.5

2.0

電子能量 [百萬電子伏特 MeV]
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High Energy Accelerators

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Synchrotron Radiation
Year 1947: First Synchrotron Radiation observed in
weak focusing synchrotron betatronse-Synchrotorns andStorage Rings forHigh Energy Physics

ALADDIN

PETRA

I
I /I
RI

A

BE

ACO/SUPER ACO

SI

BE

P
PE

MA
X

High Energy
Physics
Machines

IV

Y NS
LS
SS

P

Dedicated
Storage RinsP
LE/ IS S
SOR

PF

VE
PP

DARESBURYVEPP IIN

ADON
E

2nd G :1970-1980

SPEAR

TR
IST
A

1

CEA

1st G :1960-1970

N- SYNCHR
BO N

DORIS

CESR

3rd G :1980Low Emittance
Machines with
Insertions Devices

SPRING-8

APS

Compact
Sources

TR

TE
IES

z Straight sections for insertion
devicesz Low emittance

ES
RP

ALS

SRRC

POSTE

CH

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SR Facilities in Asia Oceania Region
BEPC (1991)
2.2-2.5 GeV

PLS (1994)

NSRL (1991)

2.5 GeV

0.8 GeVSSRF (2008)

UVSOR (1983)

3.5 GeV

0.75 GeVPF (1982)

INDUS I (1999)

2.5 GeV

0.45 GeV

SP-8 (1997)
8.0 GeV

INDUS II (2006)
2.5 GeV

SCSS (2010)
TLS (1993)
1.5 GeV

SIAM
SIAM (2004)(2004)TPS (2013)
3.0-3.3 GeV

1.2
1.2 GeV
GeV

AS (2006)
3.0 GeV

SSLS
SSLS (2001)(2001)
0.7
0.7 GeV
GeV

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Basic Parameters of Taiwan Light Source
Interval between bunches: 2ns
z Bunch length (1σ@1.6MV): 6.5mm
z Bunch duration (1σ): 21 ps
z SC Cavity length: 24 cm
z Flight time through SC cavity: 0.8nszzBunch current (180/200 filling to
Iavg=300 mA): 1.67 mA/bunch or
4.17*109 electrons/bunch

2 ns
400 ns per revolution
Zoom in
1σ = 6.5mm
or 21 ps

2 nsz

Critical energy of SR
Ec(keV) = 0.665 E2 (GeV) B(T)
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Insertion Devices

Wiggler: radiation adds incoherently (I~2N, N: number of magnet periods)
Undulator: radiation interferences coherently
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Superconducting RF Cavity
Goals：• To increase the maximum
electron beam current of thestorage ring from 240 mA to
500 mAe-e-• To eliminate beam instabilities
caused by the strong higherorder modes (HOMs) of theexisting RF cavities

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Low-emittance Medium Energy Rings
Emit.
[nmrad]C[m]Straights
m*section

Cell

StatusDate

Location

Name

E
[GeV]

2001

Switzerland,
VilligenSLS

2.4

4.8 (4.1)

288

11.76m*3+7m*3+4m*6

12 TBA

Operation

2006

France,Orsay

SOLEIL

2.75

(3.7)

351

12m*4+7m*12+3.6m*8

16 DBA

Operation

DIAMOND

3.0

6.5 (2.7)

562

11.34m*6+8.34m*18

24 DBA

Operation

2006

UK,
Oxfordshire

2008

China,
Shanghai

SSRF

3.5

7.8 (3.0)432

12m*4+6.7m*16

20 DBA

Commiss.

2009

Spain,
Barcelona

ALBA

3.0

(4.2)

268

8m*4+4.2m*12+2.6m*8

16 DBA

Construct.

2013

Taiwan,HsinchuTPS

3.0

1.7(1.46)518

12m*6+7m*18

24 DBA

Approved

2013

USA,
Brookhaven

NSLS-II

3.0

1.9 (0.5)780

8m*15+5m*15

30 DBA

Approved

7/22/2006
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Emittance of Synchrotrons

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Storage Ring

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TPS DBA Lattice Cell and Engineering Layout

DipoleQuadrupole

Sextupole

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Optical Functions and Dynamic Aperture of Three Modes
Zero dispersion, 4.9 nm-rad

Low dispersion 2.5 nm-rad

High dispersion, 1.6 nm-rad

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Brightness of Insertion Devices
光波長 (奈米、nm)
光源亮度 (Phot/s/0.1%bw/mm2/mr2/0.2A)

100

1

0.1
TPS_SU15

21

10(台灣，規劃中)TPS_U2820

TPS_EPU46

10

SP8_IVXU32
(日本)

(英國)
19

Diamond_U33

10

TPS_U100

SLS_UE56
(瑞士)

18

10

TPS_SW60 (L=2m)

17

10

TLS_EPU56

TLS_U90(台灣，現有)

16

10

3 GeV
1.5 GeV

15

10

1

10

z

10

2

10

TLS_SW60 (L=1m)
3

10

4

10

光子能量 (電子伏特、eV)

510Critical energy of SR spectrum Ec(keV) = 0.665 E2 (GeV) B(T)
TLS: 1.5 GeV, operation since Oct. 1993; the first 3rd generation synchrotron facility in Asia
TPS: 3 GeV, operation planned for 2013
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Cheiron2008_KSLiang-20

Peak Brightness [Phot./(s · mrad2 · mm2 · 0.1%bandw.)]

X-Ray FELs
InitialFuture

TLS
TPS
ERLs

3rd Gen. SR

2nd Gen. SR@10 KeV@1 KeV@20 KeVSPPS@1 KeV@10 KeV@20 KeV

FutureInitialLaser Slicing

FWHM X-Ray Pulse Duration [ps]Courtesy of H. Winick
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Electron Binding Energies

VUVSoft X-ray
Hard X-ray
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Unique Characteristics of SR+ High brilliance/flux(coherence & emittance)+ Energy tunability(element sepecificity)+ Polarization(spin probe)+ Time structure

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EXAFSχ (k ) = ∑
j

Nj

[

] [

2 2
S
(
k
)
F
(
k
)
exp(
−
2
σ
j
j k ) exp − 2 R j / λ ( k ) sin 2kR j + δ ij ( k )
2 j

kR j

]

Probe of Atomic Arrangements indisordered matters – beyond
crystallography

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Supported Metal Catalyst

金屬顆粒

0.2~2 cm

1~100 µm

10~300 Å

觸媒丸

觸媒粉末

內部孔隙

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Fuel Cell Research
燃料電池工作示意圖
Catalyst Layers (~10 µ m)

H2O

CO2
H2O

Current
Collector

CATHODE

H+

ANODE

6e-

CH3OH

CH3OH, H2O

6e-Current
Collector

Air (O2)

Diffusion Layers (~100 µm)

Pt

Co

利用X光吸收光譜分析可獲知材料中特定元
素的電子性質與局部幾何結構，並經由充放電過程之臨場量測，直接與電化學行為建立
關聯性，成為改進電極材料特性之依據。

Cheiron2008_KSLiang-34

Atomic Scattering Factors of X-rays
Atomic scattering factor f (q,E)= f0(q) + f’(E)+ i f”(E)Intensity

I ≈ FHKL = ∑ f i ⋅ e
2vv
iq HKL ⋅ri

2i

Cheiron2008_KSLiang-35

X-ray Anomalous Scattering Factor of PT
f (E) = f0 + f ' (E) + i f ' ' (E)
Pt

+

+

+
+

Element-specific diffraction pattern or X-ray partial structure factor
Cheiron2008_KSLiang-36

Anomalous X-ray Scattering
Atomic scattering factor f (q,E)= f0(q) + f’(E)+ i f”(E)= f1+i f2
Intensity

I ≈ FHKL = ∑ f i ⋅ e
2

i

v
v
iq HKL ⋅ri

2

f2

f1
E/Eedge

Chemical composition and/or electronic states
Cheiron2008_KSLiang-37

Uncapped In0.5Ga0.5As Quantum Dots
Grown by MEE

AFM image

In0.5Ga0.5As 5.85 ML/ Ga (4x2)grown @ 520oC 0.7 ML/s.
GaAs buffer layer

200 nmGaAs (001)aInAs = 6.0583Å
aGaAs = 5.65325Å

misatch = 7.2 %n ~ 5 x1010 cm-2
J. Cryst. Growth, 175/176, 777 (1997).
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A New Era of Biological Science

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The Atoms: God’s Creation

Periodic Table

U

92

Atomic bombs / nuclear power plants

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X-ray Diffraction of DNA(Rosalind Franklin)

Watson, Crick and their DNA model in 1953.

Double Helix DNA

華生與克里克(1962年諾貝爾生醫獎得主)利用X光繞射發現DNA雙螺旋結構

Source：James D. Watson , Francis Crick .
Molecular Structure of nucleic acids, Nature, 171(1953):737-138
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DNA Structure
2 hydrogen bonds

A-T

3 hydrogen bonds

Double helix DNA of 12 base pairs

G-C
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The Genome Map of living matters

Charles Darwin

Francis Collins

From “The Language of God” by F. Collins (Free Press, 2006)
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BL13B1 PX Experimental Station- for drug design

Sample Automatic Mounting System

Protein Crystal

Q-315 CCD Detector
Cryo-Cooler
X-ray Diffraction
Pattern

Fluorescence Detector
High Precision Diffractometer
Protein
Structure

Cheiron2008_KSLiang-44

Structure of SARS 3CLpro with substrate
Overall structure
Domain I

Substrate
Domain II

Active site
Domain III

Proc Natl Acad Sci U S A. 2003
Nov 11;100(23):13190-5
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Valence States of Condensed Matter

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Courtesy of Y. Wang
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Photoelectron Spectroscopy for Valence Structure1905 Albert Einsteine Vstop = hf – W
Light wave as photon

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Photoelectron Spectroscopy for Valence Structure
Fermi surfacesdσ / dΩ ∝ Σ Ψ f A• P Ψi2

δ (E f − Ei − hν )Selection rules:∆l=±1∆ ml = 0 (linearly polarized)∆ ml = +1 (L. circularly polarized)∆ ml = -1 (R. circularly polarized)

k // = 2mKE / h sin θ
2Cheiron2008_KSLiang-50

Advantages of Soft-x-ray Scattering Spectroscopy• Sensitive to spatially order of charge,
spin, and orbitals in nanometer scales

Resonant X-ray scatteringv v ikv⋅rv
v v ikv '⋅rv
0 ε ⋅ r e i i ε '⋅r e 0∆f ~ ∑hω − ( Ei − E0 − iΓ)
i

v
k

i

v
empty valence k '0core level
Cheiron2008_KSLiang-51

chargecharge ordering: spatial
localization of the charge
carriers on certain sites

lattice

2+
3+

spin

orbitalorbital ordering:
periodic arrangementof specific electron
orbitalsspin ordering: longrange ordering of
local magnetic
moments

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Nano Imaging by X-rays

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Amorphous MoS3
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The scaled absorption cross-section as a function of photon energy for a selection of elements.
The absorption cross-section per atom, σa, has been scaled by dividing it by the atomic
number Z to the fourth power, and multiplying it by the photon energy ε to the third power.
From “Elements of Modern X-Ray Physics” by J. Als-Nielsen and D. McMorrow (Wiley 2001)
Cheiron2008_KSLiang-55

Zone plate consists of concentric rings (zones) withzone width decreasing with radius
Zone Plate

Zone Plate Equations

Focus

f : focal lengthn : zone index
λ : wavelengthm : diffraction orderr : radius of the zone plate
drn: outermost zone width
Zone Radius

Spatial Resolution
Focal Length
Numerical Aperturern = ( n f λ )1/2
dm = 1.22drn /m
fm = 2 r dr / (m λ)NA = λ / (2 dr)When NA <<1, the ZP can be treated like an ordinary refractive lens,i.e., 1/q + 1/p = 1/f and M = p/q.

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Nano-TXM at NSRRC
Phase Ring

Zone Plate

10 cm
Sample Stage

Condenser Tube
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Nanotomography comes of age
2μmNews and views in
NATURE, Vol. 442, 10 August 2006

350nm
250n
m
500n
m

400nm

APL 88, 241115 (2006)
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「Light」

Refraction index : n = 1-δ-iβz

E(z)=E0e-i2π(-δ-iβ) z/ λ =E0ei2πδz/ λ -2πβz/

λI(z) ∼|E(z)|2 ∼I0e4πβz/ λCheiron2008_KSLiang-59

Phase Problem
Intensity 1

FFT-1

FFT
Phase 1

Image 1

Intensity 2

FFT

FFT-1
Phase 2

Image 2Cheiron2008_KSLiang-60

8μm

Wilhelm Röntgen @1894

Lung ancer cell
(NSRRC)

Cheiron2008_KSLiang-61

Solution of Phase Problem by Coherent Diffraction Imaging
Coherent wave field propagation
z<d2/
λ

z~d2/
λ

z>d2/
λ

d – sample size;
λ – wavelength;z – distance from sample

Kinematic approximation
In the Fraunhofer region complex
wavefield is proportional to the
Fourier transform of:- projected electron density (X-ray)- projected Coulomb potential (e-)

ModulusPhase problem

ObjectPhase
Exit wave

Ψ(x, y )FT
FT-1

Far-field

˜ (u,v )Ψ

Detectors measure only diffracted
intensity and the phase is lost.
2˜I (u,v ) = Ψ(u,v )Cheiron2008_KSLiang-62

Solution of Phase Problem by CDI
Real spaceρ(x, y ) = ∫ F (qx ,qy )exp −i2π (xqx + yqy ) dqx dqy()

Fourier space
F (qx ,qy ) = ∫ ρ(x, y )exp(i2π (xqx + yqy ))dxdy

Iexp (qx ,qy )= F (qx ,qy )

2

⎡ 2πi
⎤
F (qx ,qy ) = ∑ ∑ ρ (x, y )exp⎢
q
x
+
q
y
(
y )⎥
⎣N x
⎦
x=1 y=1
N

Solve system of N2 nonlinear equations

NN
N

N2 - unknown variables

known < unknown
2N2
N2

N2 - known variables (modulus)
N2 - unknown variables (phases)

2N
Isolated finite sample

2N

known > unknown
7N2

N2 - unknown variables
3* N2 - known variables (zero)

5N2

by Iterativealgorithms

4* N2 - known variables (modulus)
4* N2 - unknown variables (phases)

Cheiron2008_KSLiang-63

CXDI Experiment at BL12XU, SPring-8-- D. Noh, KIST

Diffraction Pattern of ~2.5 um spacing Au dotson Si3N4 membrane- E = 7.5 KeV- 1.17m Sample to CCD distance- Centro-symmetry

Reconstructed image- HIO Algorithm (170 iteration)- Center Patched

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Electron Coherent Diffractive Imaging ofSingle MgO Nano-Particle

Nano-area electron diffraction (NED)

TEM image of the electron nanoprobe

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Nano-Area Electron Diffraction Experiment
Recorded diffraction pattern from MgO near the [001] zone axis
200

0-20

0.94 A

0-20(size ~ 17 nm)

200

220

-220

020

020

Camera length – 100 cm. Exposure time – 3 seconds. Cheiron2008_KSLiang-66

Phase recovery at atomic resolution??
Recovered by CDI exit surface wave function of MgO nano-particle
Modulus

Modulus (red color) and phase (bluecolor) of the exit wave integrated alongcorresponding rectangular selection

Phase

Enlarged view of the exit wave indicated by square
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Surface roughness of water measured by x-ray reflectivity
A. Braslaw, et al., PRL 54 (1985)

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+ The prism: Energy Analyzer (energy resolution)+ The eye: Detector (sensitivity)z

Inelastic X-ray Scattering
an energy resolution 107 with 10 keV photons
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Oct. 21, 2005, 7am @ BL17C

Do not waste photons and have fun at experiments!
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The End

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