Cheiron School, SPring-8, Japan
October 2, 2011

Studies on atoms and molecules
using synchrotron radiation
Kiyoshi Ueda
Institute of multidisciplinary research for advanced materials
Tohoku University, Sendai 980-8577, Japan

Introduction of myself

Prof. Kiyoshi Uedaat
Tohoku University （Sendai）
Institute of multidisciplinary research
for advanced materials
Leadinga research group for electron andmolecular dynamics

Atomic and molecular science using
Synchrotron Radiation
Ueda, JPB 36, R1 (2003);
Ueda & Eland, JPB 38, S839 (2005);
Ueda, JPSJ 75, 032001 (2006);
Kabachnik et al. PR 451, 155 (2007).
Application of the SR-based
experimental techniques to laser
experiments(femtosecond laser and FEL)

Outline
1. Introduction to quantum world
2. Atomic resonant photoemission spectroscopy- Introduction to the quantum interference
3. Vibrationally-resolved core-level photoelectron spectroscopy- Adiabatic approximation and Franck-Condon analysis- Young’s double-slit experiments
4. Multiple-ion momentum imaging- Snapshots of molecular deformation within a few fs
5. Electron-ion momentum imaging- Molecular-frame photoelectron angular distributions
6. Interatomic Coulombic decay
7. Towards single shot molecular imaging by XFELPhotoelectric effect
When matter is shined by the light, electron isemitted from the surface.
(i) Frequency of the light needs to be larger than ν0.
(ii) Kinetic energy of the electron is determined by thefrequency of the light.
(iii) Number of electrons is proportional to the intensityof the light.

Einstein’s explanation
Light at frequency of ν is considered to be a group ofparticles (photons) and each photon has energy hν.
An electron gets the energy hν when it absorb one
photon.
The electron in the matter is bound. For the electron
to be emitted from the matter, the electron needs toreceive the energy more than the work function W.
Then the kinetic energy KE of the emitted electron canbe given as KE = hν – W.

Photoelectron spectroscopy (UPS, XPS)
Precision measurements for kinetic energies of photoelectrons
emitted via Einstein’s photoelectric effects

Kinetic
energyPhotoelectron
spectrum

Vacuum level
Intensity
Valence level

BindingenergyBalmer and Rydberg formulae

Balmer found beautiful regularity in the H spectrum!

ν

1 
 1
= = R 2 − 2 
Rydberg formula：
c λ
n' 
n
1

c, speed of light; λ, wavelength; R, Rydberg constant (R =109737.309 cm-1)

Bohr’s atomic model
Electron orbits exist only when the classical orbits satisfy thefollowing condition of quantization:
2π∫ pϕ dϕ = nh
0ϕ, angle of rotation; pϕ= mer2dϕ/dt , angular momentum; r, radius; me, electron mass

The electron binding energies are discrete:
Ēn= -hcR/n2

ド･ブロイ定在波とボーアの量子条件
2π

量子条件：

∫ pϕ dϕ = nh

λ =h/p2πrn = nλ = nh/p = nh/mv

0Schrödinger equation of H atom (in atomic units)HΨ(r) = EΨ(r)H = T + U (r )Hamiltonian

p2
1 ∂2
T=
=−
2
2
2 ∂r

kinetic energy

∂
p=i
∂r

momentum1
U (r) = −rpotential energy

1
En = − 22n

Ψ: wave function
complex number (with phase!)Atomic and molecular science now
Target: single atom or molecule; size: ~ 1 Å (= 0.1 nm = 10-10 m)

How to use synchrotron radiation to study atoms and molecules
We use monochromatic synchrotron radiation to excite atoms
and molecules and to study their electronic structures as wellas electron and nuclear dynamics in the excited states.
A single photon should be absorbed by a single atom ormolecule first!

What photon energies to be used
Electron binding energies (eV)

Vacuum ultraviolet light!

The experiments need
to be in the vacuum!
SR

Ion
detector

Mol. Beam

The easiest experiment:
ion yield spectroscopySPring-8 BL27SU
Figure-8 undulator
Linearly polarized light
Horizontal polarization (1st)Vertical polarization (0.5th)
T. Tanaka and H. Kitamura, J. Synchrotron Radiation 3, 47 (1996).

Soft X-ray monochromator
Hettrick type: varied line spacing plane grating
Energy range

0.15 ~ 2.5 keV

Photon Flux

> 1011 photon/s

Energy resolution

10000 - 20000

H. Ohashi, Y. Tamenori, E. Ishiguro et al. Nucl. Instr. Methods A 467, 533 (2001).

Ne 1s total ion yield spectrum
np Rydberg series- Ēn = IP – En = R/(n-µ)2µ : quantum defect R =13.6 eV

IP

Σ

σn
σ = σdir++ σ1s ε = (hν-En)/(Γn/2)21+εnn
σn ∝ 1 /(n − µ )3
Γn= const!

Auger decay and Auger electron spectroscopy
photoelectronCore hole lifetime
defines the line width!

Auger electron

SES2002 analyzer•

Electrostatic hemisphericalanalyzer– Mean radius 200 mm– ∆E/PE=1/1600(66 meV at pass 100 eV)– MCP+CCD cameraor MCP+Delay line anode– Gas cell system
or Doppler-free molecular beamsourceUeda et al. PRL . 90, 153005(2003)
or effusive beam + momentum
resolved ion spectrometer
Prümper et al. PRA 71, 052704,(2005).

Angle-resolved resonant Auger spectra of Ne at
1s -> 3p excitation

2p-2(1D2)3p

P2 (cos θ ) = [3 cos θ − 1] / 2
β: asymmetry parameter
Measured angular distributions tell us how theangular momenta are coupled in the atom ,allowing us the spectroscopic assignment !

Resonant Auger spectra of Ne “between”
1s -> 3p and 1s -> 4p excitationsσ ∝ I (0) + 2 × I (90)2p-2(1D2)3p

Interference effects between the two paths
Αα = dα+σα = |Αα |2

Σn

Dnα
i+εn

εn = (hν-En)/(Γn/2)
dα = <g|r|α>Dnα = <g|r|in><in|v|α>
|i>

|α>

Dnα
dα
|g>

De Fanis et al. Phys. Rev. Lett. 89, 023006 (2002).

Sendai City

Statue of Load Date

Jozenji Street

Introduction of molecular worldHΨ( R, r ) = EΨ( R, r )h∂2
TR = − ∑2 k Mk ∂Rk2

KE of nucleus

H = TR + Tr + V (r, R)h∂2
Tr = −∑
2m j ∂rj2

KE of electrons

H 0 = Tr + V (r , R)

H = H 0 + TR

[ H 0 − ε n ( R )]ϕ ( R, r ) = 0
ε n (R ) : adiabatic potential energyΨ ( R, r ) = ∑ Φ n ( R)ϕ n ( R, r )n[TR + ε m ( R)]Φ ( R) = E Φ ( R)
0
mv

0
mv

0
mv

Nuclear motion is within the adiabatic potential energy surface!

Born-Oppenheimer approximation

Franck-Condon approximation for photoionization

σ iv+' (E) ~| ∫ X iv* ' (R)DE (R) X 0 (R)dR |2

Xiv* ' (R), X 0 ( R) : Vibrational wavefunctions of ionic iv’ and ground 0 states

D E ( R ) = ∫ ϕ E* ( r , R ) r ϕ core ( r , R ) d r

ϕ E ( r , R ), ϕ core ( r , R ) : Electronic wavefunctions of the continuum E and core orbitals
Assume that the dipole moment DE(R) does not depend on R

σ iv+' (E) ~| DE ( Re ) |2 F (v'0)
F ( v '0 ) = | ∫ X iv* ' ( R ) X 0 ( R ) d R |2 Franck-Condon factor
Vibrational intensity distribution in the photoelectron
spectrum is determined by the Franck-Condon factors

Franck-Condon analysis based on harmonic approximation
Linear coupling model
Intensityν‘ = 2

F (1,0) =Ionic stateν‘ = 1α ( ∆R ) 22

 α ( ∆R ) 2 exp −2 α = µω hν‘ = 0∆R

Photoelectron
spectrumElectronic
ground state

ν=0R0 α ( ∆R ) 2 
F (0,0) = exp −2 

F(1,0) α(∆R)=
F(0,0)
2

2

R'0

Internuclear distanceOne can extract ∆R from photoelectron spectroscopy!

Franck-Condon analysis for the vibrational structureof the C 1s and O 1s mainlines of COΙ ∼|<ψ+v|ψ0>|2 : FC factor
ψ0: v=0 vibrational wave functionin the ground stateψ + v: v-th vibrational wave functionin the core-ionized state
Stable geometry of the core-ionized state
extracted from the vibrational structure
Exper.

TheoryC 1s-1∆Re (Å) -0.051 (1)-0.051O 1s-1∆Re (Å) 0.037(2)0.028Matsumoto et al. Chem. Phys. Lett. 417, 89-93 (2006).

Satellite spectrum in core-level photoemission in CO

HOMO-LUMO

π−π∗Mainline

Ehara et al. J. Chem. Phys. 125, 114304 (2006).

Franck-Condon analysis of the vibrational structure in
the symmetry-resolved C 1s satellite bands of CO

Solid lines: measured
symmetry resolved
spectraVertical bars: ab initio
FC factors

Ab initio potential curves

Ab initio FC factors reproduce themeasured vibrational distributions.
Ueda et al., Phys. Rev. Lett. 94, 243004 (2005).

N(1)Evidence of the dualityof waves and particles!

N(2)Electrons also showinterference fringes!

Evidence that the light is the wave!

Franck-Condon analysis for the vibrational structureof the N 1s 1σu and 1σg mainlines of N2
2500

1500
1000
500
0

90.0

90.5

91.0

Kinetic energy (eV)-1

Relative intensity

Counts2000

N2 N 1shν=500 eV

(1σu)
-1
(1σg)

SAC-CI
v’=0

Exper.

v’=1
90.0

90.5

Equilibrium geometries of the core-ionizedstates extracted from the vibrational structure

91.0

Kinetic energy (eV)N 1σu-1∆Re (Å) -0.023(1)N 1σg-1∆Re (Å) -0.018(1)Theory-0.021-0.017

Ehara et al. JCP 124, 124311 (2006)

Cohen-Fano two-center interference
Two 1s ortibals in N2 correspond to Young’s double slits.
Molecular core-level ortibals:
Core-level photoemission from fixed-in-space N2:

Two center photoelectron wave

Interference fringe

where k: photoelectron momentum; R1,R2: position vectors of N (1) and N(2)Orientational average: Cohen-Fano formulaInterference oscillatory structure becomes much smaller but remains!
H.D. Cohen and U. Fano, Phys. Rev. 150, 30 (1966).

Ab initio N 1s 1σu and 1σg photoionization cross sections of N2

Oscillation:
Two-center Interference
Cohen-Fano prediction !

Semenov et al., J. Phys. B: At. Mol. Opt. Phys. 39, L261 (2006)

σg /σu ratio: experiment vs ab initio and Cohen-Fano
2.2

N2 K shell/
Experiment
Original Cohen-Fano
RPA

Cross section ratio σg/σu

2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
1

2

3

4

5

6

Electron momentum (a.u.)
Both experimental and ab initio interference fringes shift from the prediction
by Cohen-Fano formula!
Liu et al., J. Phys. B. 39, 4801-4817 (2006); JESRP 156-158, 73-77 (2007).

Photoelectron scattering by the neighboring N atom
The amplitude of the photoelectron wave from one center:

A1ψ2 = Α2+Β2

B1

The amplitude of the photoelectron wave from two centers: ψ1 ± ψ2

Cohen-Fano interference
A1A2 interference term
N(1)

N(2)

N(1)

N(2)

The cross section~ |ψ1 ± ψ2 |2 = |(Α1+Β1) ±(Α2+Β2) |2

0

A1B1 and A2B2 one-center interference terms

δ1(k): scattering phase
CF A1A2 interference term

A1B2 and A2B1 two-center interference terms !

Sendaiin summer

Tanabata festival

Multiple--ion coincidence imaging setup
MultipleE field

Y Ion 2D

field free
TOF tubehν electron
MCP

PSD
x2y2t2
x1y1t1t0

t, Z 80mm

x4y4t4X
x3y3t3supersonic jet

25

70skimmer

140 mmSample gas jet
position & time of flight (x,y,t)

3D momentum of each particle

How to obtain 3D momentum

t: ion time-of-flight6

to: ion TOF at rest

TOF of 2nd ion ((µs)
24m (x − x0 )m ( y − y0 )px =, py =, p z = qE (t − t0 )ttx, y: arrival position on the detector.
x0, y0 : initial position of the ion
m : ion mass
q: ion charge

O+ + CO+C+ + O+

E: electric field in the acceleration region
2

4

TOF of 1st ion (µs)

To be exact Pz becomes nonlinear

Iterative procedure6

Total electron yield spectrum of CO2 in the C1s excitation region
CO2 ground state configuration:
1σg21σu22σg23σg22σu24σg2
O1s

C1s

O2s

C2s

3σu21πu41πg4(1Σg+); 2πu05σg04σu0
2πu ← 2σg resonanceIntensity (arb. units)

π*

TIY

297.63 eV
C K-edge

4σu ← 2σσ
shaperesonance
shaperesonanceu g-

2e exc.

290

295

300

305

310

315

Photon energy (eV)

320

325

O

Renner--Teller splitting of CO2
RennerC

Out-of-plane 2ππu: B1E

CO2 C1s-1 2ππuOBending plane ⊥ E

In-plane 2π
πu : A1OO

CO2 Ground stateFranck-Condon
regionE

C
Bending plane // E

CO23+ -> C+ + O+ + O+
180º
Bond angleSnapshot of the bending motion in the corecore-exited statewith a liftetime ~7 fs
Newton DiagramOut-of-plane 2ππu: B1
LinearIn-plane 2π
πu : A1
Bent

Muramatsu et al. Phys. Rev. Lett. 88, 133002 (2002).

Electron--ion coincidence momentum imaging
ElectronMultihit 2D detector

Multihit 2D detector
Electric field

Y

Y

N+
B
e-

B+
e- N
O+
A

O+
A

X

X
X-raysMagnetic field

IonIon-ion coincidence

Molecular axis

Ion momentum conservation

Retrieval of the source point

Electron--ionElectron
ion-ion coincidence

Molecular--frame e- angular distribution
Molecular

Towards photoelectron diffraction measurement

Total electron yield spectrum of CO2 in the C1s ionization region

4σu ← 2σg shape resonance
CO2 ground state configuration:
1σg21σu22σg23σg22σu24σg2
O1s

C1s

O2s

C2s

3σu21πu41πg4(1Σg+); 2πu05σg04σu0
C 1s threshold
297.63 eV

N. Saito et al., J. Phys. B, 36 L25 (2003).

Reaction plane
Reaction plane ＝plane define by the E vector and molecular axise-θElectric vector

Electron emission
direction

O

θn
C

O
Molecular axis

We focus on the electron emission within this reaction planeC1s photoelectron diffraction (MFPAD) of CO2:
comparison between experiment and theory
Photon energy

Shaperesonance

The general agreement between experiment and theory is reasonable.
At the shape resonance, the intensity drops at θn =90° i.e. Σ-Σ paralleltransition. The intensity drops at θ = 90 ° , i.e., σu photoelectron wave !

Satellite line vs Main line
Y axis： θehν = 312.2 eV

8000

countse-

X axis： θnPhotoelectron spectrum
6000
4000
2000
0
0

5

10

15

20

electron kinetic energy

Satellite

Mainline

180

θe

180

135

135

90

θ e 90Emission
perpendicular to
the molecular axis

45
0
0

45

θ n90

135

Emission along
the molecular axis

45
0
180

0

45

θ n90

135

180

In both cases, the intensity drop at θn =90° i.e. Σ−Σ parallel transition.
The electron emission directions are completely different.
Liu et al. Phys. Rev. Lett. 101, 023001 (2008).

Near Sendai

Motsu-jiMatsushima bay

Mount Zao

Chuson-jiAuger vs Interatomic Coulombic Decay (ICD)

Ne

Intra-atomic

high-energy Auger e-

Energy transfer via
virtual photon exchange

low-energy ICD e-

ICD rate is R dependent!

Why is ICD important?
ICD: electronic decay where the environment plays a role!
ICD takes place in van der Waals clusters, in hydrogen bonding clusters, inmetallofullerenes, in bio-molecules in the living cell, etc
ICD is everywhere!
ICD is one of the key players in energy and charge transfer in these systems.

Metal atom in C60

Interatomic Coulombic Decay (ICD)
TheoreticalFirst prediction - HF cluster:
L.S. Cederbaum, J. Zobeley, and F. Tarantelli, Phys. Rev. Lett. 79, 4778 (1997).
Prediction - Ne dimer:
R. Santra, J. Zobeley, L.S. Cederbaum et al., Phys. Rev. Lett. 85, 4490 (2000).

Experimental
First observation - Ne cluster:U. Hergenhahn and coworkers, Phys.Rev. Lett. 90, 203401 (2003).
Cluster-size-dependent lifetime:
G. Öhrwall et al., Phys. Rev. Lett. 93, 173401 (2004).
Ne2 e-ion-ion coincidence:
R. Dörner and coworkers, Phys. Rev. Lett. 93, 163401 (2004).

Observation of ICD in Ne2 by Frankfurt group
Ne2+ (2p-2)
Ne+ (2s-1)

5.16 eVICD Ne+(2p-1) + Ne+(2p-1)

40

+

-1

Ne (2p )20

0Potential energy

エネルギーレベル (eV)

60

AB*

(a) (b)KE(e)KER
A+ + BR
KE(e)+KER = 5.16 eV

Ne+

Ne+

Electron-ion-ion coincidence momentum imaging

T. Jahnke et al.
Phys. Rev. Lett.
93, 163401 (2004)

Interatomic Coulombic Decay after Auger decay
Prediction - ICD from Auger final states in Ne dimer:
R. Santra and L.S. Cederbaum, Phys. Rev. Lett. 90, 153401 (2003).

Why is ICD after Auger decay interesting and important?
Radiation damage caused in biobio-molecules in the living cell
Radiation damage, caused by e.g., X-ray radiation, is initiated by core ionization.
Radiation damage is known to be caused by low energy electron collisions, not high energy
Auger electrons.
ICD is one of the important mechanisms to produce low energy electrons after Auger decay!

Labeling electron emission site via the ionic charge state[A+(core-1)-A] +e-Photo −> [A2+ - A] +e-Auger −> [A2+ + A+] + e-ICD
Is the ICD electron ejected from the A+ site or A2+ ?
Can the A+ or A2+ be which-way information of the double slit experiment ?
We can experimentally answer to this very basic question!

Experimental evidence of interatomic Coulombic
decay from the Auger final states in argon dimers(a) Core photoionization and Auger decay

2p ionization

Auger(b) Interatomic Coulombic decay
ICD electron
virtual photon

SPring-8 view from sky

ICDMorishita et al. Phys. Rev. Lett. 96, 243402 (2006).

(c) Fragmentation

Ar2+

Ar+
fragmentation
We detect ICD electrons in coincidence with Ar+ and Ar2+
using e-i-i coincidence momentum spectroscopy

Multiple coincidence momentum imaging
Multihit 2D detector

Multihit 2D detector
Electric field

Y

Y

N+
B
e-

B+
e- N
O+
A

O+
A

X

X
X-raysMagnetic fieldposition & time of flight (x,y,t)Multiple coincidence
Momentum conservation

3D momentum of each particle
Momentum correlation
among the particles
Selection of Dimer from others !

TOF of Second Ion ((µs)

Ar2

PIPICO spectrum

864
filtering
22

4
6
TOF of First Ion (µs)
Filter conditions:
Ar+/Ar+: the sum of the momentumof Ar+ and Ar+ ~ 0
Ar++/Ar+: the sum of the momentumof Ar++ and Ar+ ~ 0

Ar++/Ar+ comes from ICD !?

Electron spectrum, KER, and their correlation
Electron spectrum coincident with Ar++/Ar+

Equilibrium distance
3.8 A ++Ar+Ar
Coulomb explosion( expected KER ~ 7.6 eV)
KER
Ar++/Ar+
Measured KER~ 7.7 eV

ICD: KER + KE(ICD electron) ~ constantIslands of slope -1 are ICDs !

Breakup following ICD takes placealmost instantaneously.

ICD is very fast!

Photoelectron ejection(13.4 and 11.3 eV)

Potential energy

Energy diagram of
the ICD process in Ar2

Binding Energy (eV)80

hv=262 eVphotoionization

3s-2
3p-33d(１P)70(a) (b)
KE(e)

Ar3+

Auger decay

2p-1

AB*

R

ICD &
fragmentation

CI
3s-13p-1 (１P) 10eV

60

KER
A+ + B

3p-1 & 3p-2 (１D)

50

3p-2
40

Ar

Ar+

Ar

Ar2+

KER
+ ICD electron= 10 eVAr+

Ar2+

ICD from the Auger final states in Ne dimerNe+＋

1s photo-e

Ne

BESSY

Auger
Ne+＋

Ne＋

Kreidi et al. J. Phys. B. 41, 101002 (2008).

ICD

Ne++

Ne+
fragmentation

We detect ICD electrons in coincidence with Ne+ andNe2+using e-i-i coincidence momentum spectroscopy

ICD channels in Ne2 after KL1L23 Auger
Ee1

Ee1 + KER = 11.2 eV
1

R~R0

1

2

Ne + + (2 s −1 2 p −1 P ) - Ne − > Ne + + (2 p −1 2 p −1 D ) - Ne + (2 p −1 P )1s photo-e

98.5 eV − (65.7 + 21.6) eV = 11.2 eV

Ee1 + KER = 14.4 eV
1

32

Ne + + (2 s −1 2 p −1 P ) - Ne − > Ne + + (2 p −1 2 p −1 P ) - Ne + ( 2 p −1 P )KER~9.5 eV~13 eV

98.5 eV − (63.5 + 21.6) eV = 14.4 eV
1KER

Spin flip!

Ee1

ICD-e

3

Ne + + (2s −1 2 p −1 P) − > Ne + + (2 p −1 2 p −1 P)

after bond shortening

Exchange !

KER + Ee1

R~2.2 A < R0 = 3.2 A

Molecular frame electron angular distributions
emitted via ICD
ICD by virtual photon exchange(direct integral)
ICD electron is emitted from Ne+ site

Ne++

Ne+

ICD by electron transfer(exchange integral)
ICD electron is emitted from Ne++ site

Ne++

Ne+

Flipped!

Ne+

Ne++

Ne+

Ne++

Wave packet dynamics on ab initio
potential energy curves

Stoychev et al. J. Chem. Phys. 129, 074307 (2008).

Exchange ICD
Direct ICD
Electron transfer Virtual photon exchange
Ne++(2s-1 2p-1 1P)
Ne++(2p-2 3P)+ Ne+(2p-1 2P)

Ne++(2p-2 1D)+ Ne+(2p-1 2P)

Heidelberg U. ICD gangs in Germany and Japan ! AIST

Alex
Lenz

Spas

Yuichiro

Norio

Frankfurt U.

Reinhard

Markus

Kathi

Till

HIroshi

Kyoto U.

Tohoku U.

Hironobu

KentaroGeorg

Xiao-Jing

Kiyonobu

Ultrafast imaging of asingle molecule using
XFEL
SCSS
2009

2011

DESY X-FEL

2013

Coherent XX-ray diffraction imaging of a single molecule
Neutze, Wouts, van der Spoel, Weckert, Hajdu Nature 406, 752 (2000)
Gösta Huldt, Abraham Szöke, Janos Hajdu (J.Struct Biol, 2003 02-ERD-047)

XFEL
Recording the image
before explosion

Classification by themolecular orientation

Averaging

X-ray detector

Combining the images
for different orientation

Ion momentum imaging might help for classification….

Reconstruction

Coherent diffractive imaging, Coulomb explosion imaging
and electron diffraction
Ion detector

View from upper side
X-ray detector
Large anglehν

Small angle

XFEL

XFEL

Cluster source
Low-temp.
High-temp.
Cluster/Molecular
beamElectron detector

Particle size：10-50 nm

ESI forbiomolecules
High resolution e-TOFs

CEI may provide us with the information about spatial alignment of the molecule

SCSS test accelerator : EUVEUV-FEL (51(51--61 nm)
Momentum imaging
apparatus￥

EUV-FELMultiple ionization of Ne-Ar mixed clusters@ 20 eV photon energy
Ne cannot be ionized by single photoabsorption of 20 eV photons.

Ionization energy of Ne = 21.56 eV
Ionization energy of Ar = 15.76 eV

Kinetic energy distributions of Ne+
from Ne-Ar mixed clusters @ 20 eV
pure NeNe + Ar 1%
Ne + Ar 3%

Rrelative intensity

0.010
0.008
0.006
0.004
0.002
0.000
0

20

40

60

80

Kinetic energy (eV)Average kinetic energy of Ne+ increases with increasing theamount of Ar.

Charge state of the cluster increases.

Ne+ yields increase with increasing
the amount of Ar.

Charge transfer from Ar to Ne
occurs.

Collaborators
Tohoku U.
H. Fukuzzwa
X.-J. Liu
K. Motomura
G. Prümper
C.WangA. Yamada
M. Okunishi
K. Shimada
K. UedaApparatus&
Measurements

Kyoto U.
K. Nagaya
H. Iwayama
A. Sugishima
H. Murakami
M. YaoCluster source

Tohoku U.
T. Harada
M. Toyoda
M. Yanagihara
M. Yamamoto
OpticsLBL.
A. Belkacem
OpticsAIST
N. Saito
Analysis
software

MPG ASG CFEL
/ MPI Heidelberg
A. Rudenko
K.-U. Kühnel
M. Kurka
J. Ullrich
Measurements
Frankfurt U.
L. Foucar
A. CzashO. Jagutzki
H. Shimidt-Böcking
R. Dörner
Acquisition software

Uppsala U.
R. Feifel

Measurements
RIKEN
M. Nagasono
K. TonoA. Higashiya
T. Togashi
M. Yabashi
T. Ishikawa
T. Tanaka
Light source
RIKEN/JASRI
H. Kimura
H. Ohashi
Beam line

Special Thanks
RIKEN SCSS test accelerator operation group; IMRAM technicalservice section, Tohoku U.; LBL optics group.

The endThank you very much for your attention!