Kiyoshi Ueda and Georg Pr

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My task is to give a short presentation
describing examples of experiments enabled by
4GLS and not feasible with 3rd Generation Light
Source like SPring-8.
Studying and controlling ultrafast phenomena in
atoms and molecules
- Our proposal for the experiments with 4GLS -

• Kiyoshi Ueda and Georg Prümper

Inst. Multidisciplinary Research for Advanced
Materials, Tohoku University, Japan
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Outline
1. Introduction to time-resolved photoelectron
spectroscopy and coherent control
2. Coherent control with phase-coherent double
pulses
3. Time-resolved photoelectron spectroscopy
using core-hole lifetime as a stopwatch
4. Summery and future prospects for atomic and
molecular science and photochemistry with 4GLS
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Conventional time-resolved pump-probe
measurement for vibrational motion in I2 molecules
Introduction time-resolved
Zewails Femtochemistry in 1990s
Femtosecond time-resolved pump-probe experiments
made a nuclear motion of a molecular system
visible.
Intensity(arb.)
Revisit to Zewails Novel prize experiment.
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Femtoseond time-resolved PES
One-step beyond Femtochemistry on nuclear
motions is
A change in molecular conformation causes charge
redistributions and rearranges the electronic
structure.
This is what femtosecond time-resolved
photoelectron spectroscopy can probe!
4GLS!
What we need is IR-UV pulse for pump (for
vibrational/e/electronic excitation) VUV pulse
for probe (for photoelectron spectroscopy)
A momentum correlation coincidence technique,
where we use atomic core hole lifetime as a
clock, starts to probe the evolution of
electronic structure via the molecular
dissociation.
This preliminary result gives us a starting point
of developing a new field which should be
explored with 4GLS!
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Introduction coherent control
Use of a liquid crystal phase modulator genetic
algorithm
The results of control often end up with a
double-pulse sequence. The first pulse initiates
the nuclear motion.One needs to wait until the
wave-packet comes to the right position such as a
potential crossing point. Then the second pulse
can guide the packet which way to go.
Then why dont we use phase-coherent double
pulses for coherent control ?
The advantage for use of phase-coherent double
pulses Instead of liquid crystal phase
modulator, one needs an interferometer, which is
now available in VUV (and even in soft X-ray)
regions.
Why dont we install in 4GLS an interferometer
for making phase-coherent double pulses for
coherent control ?
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Splitting one pulse into two pulses with time
delay
EXPERIMENTAL CHAMBER
Photon beam from 4GLS (FT limit coherent pulse)
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Time independent picture
l0
adjusted to the electronic transition.
Frequency comb is made by the interferometer.
Lets irradiate the molecule with this light !
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2
Vibronic excitation takes place !
No excitation takes place !
1
1
dnl0
d(n0.5) l0
0
0
7.43
7.39
7.41
Angular Frequency (fs-1)
Angular Frequency (fs-1)
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Time dependent picture
Tvibvibrational period
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Experimental scheme and pump-probe setup for the
wave-packet interferometry
APM Omori et al. PRL 91, 243003 (2003)
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Vibrational wave-packet interference
Model calculation of vibrational wave packet
interference
Expected signals (schematic)
Intensity(arb.)
Observed signals
Intensity(arb.)
Intensity(arb.)
tprobe/fs
tprobe/fs
First observation of the vibrational wave-packet
interference !
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Message One can manipulate and control
vibrational wave-packet interference with phase
coherent double pulses. One can apply this
technique to coherent control of any other
quantum processes, such as photoionization,
molecular dissociation, etc.
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Credits
Real-time observation of phase-controlled
vibrational wave-packets in iodine molecules
Y. Sato, H. Chiba, M. Honda, Y.Hagihara, K.
Fujiwara, K. Ohmori, and K. UedaTohoku
University and CREST Ultrafast Phenomena XIV,
Proc. for 14th Intern. Conf. (Springer series in
Chem. Phys.2004) p. 526.
Real-time observation of the phase-controlled
molecular wave-packet interference
K. Ohmori, H. Katsuki, H. Chiba, M. Honda, Y.
Hagihara, K. Fujiwara, Y. Sato, and K. Ueda
IMS, Tohoku University and CREST
Phys. Rev. Lett. submitted
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Location of SPring-8
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SPring-8 view from sky
BL27SU state-of-the-art soft X-ray beamline
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Ultra-fast dissociation of core-excited molecules
Case study SF6
F1s-1s

• resonant inner shell excitation
• F 1s -gt sC-F at hn 700 eV
• 2) fragmentation
• 2 10 fs
• 3) emission of an F 1s Auger electron
• 3 fs

(2) and (3) have no strict order The time scale
depends on the excitation energy. One can use
De-tuning to control the Ultrafast
dissociation!
SF6
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Controlling ultrafast dissociation by de-tuning
Dissociation dynamics probed by Doppler effects
as a function of detuning
fast
slow
The fragmentation speed changes as a function of
detuning.
SF6 F 1s -gt sS-F
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Doppler profile analysis
q the angle between the momentum k of the Auger
electron and the velocity vector v of F
Polarization (b anisotropy parameter of F)
Anisotropy of Auger emission in molecular frame
z decreases to zero from negative to positive
detuning!
We are probing the transition from molecular
region to atomic limit.
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Message this detuning experiment gives the
information equivalent with time resolved
photoemission spectroscopy!
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Coincidence experiment
Momentum correlation
Coincidence map x-axis electron energy y-axis
ion momentum
The electron shift tells us the momentumof the
emitter!
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The coincidence data for CF4
Acceleration of F is faster than Auger-decay.
Direct measurement of theDoppler shift by center
ofmass determination.
early/late asymmetry Evidence of
intramolecular-scattering!
A first step of an electron diffraction
experiment for the molecule in the process of
dissociation, using an atomic core-hole clock!
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Credits
Anisotropic ultrafast dissociation probed by the
Doppler effect in resonant photoemission from CF4
K. Ueda, M. Kitajima, A. De Fanis, T. Furuta, T.
Shindo, H. Tanaka, R. Feifel, S. Sorensen, H.
Yoshida, and Y. Senda
Phys. Rev. Lett. 90, 233006 (2003).
Doppler effect in resonant photoemission from
SF6 correlation between Doppler profile and
anisotropy of Auger emission
M. Kitajima, K. Ueda, A. De Fanis, T. Furuta, T.
Shindo, H. Tanaka, K. Okada, R. Feifel, S.
Sorensen, F. Gel'mukhanov, A. Baev, and H. Agren
Phys. Rev. Lett. 91, 213003 (2003).
Ultrafast dissociation of F 1s excited SF6 probed
by electron ion momentum coincidence spectroscopy
G. Prümper, Y. Tamenori, A. De Fanis, U.
Hergenhahn, M. Kitajima, M. Hoshino, H. Tanaka,
and K. Ueda
J. Phys. B At. Mol. Opt. Phys. 38, 1 (2005).
Intra-molecular Auger-electron scattering in the
ultrafast dissociation of CF4 at the 1s -gt a1
Excitation
G. Prümper, K.Ueda, Y. Tamenori, M. Kitajima, N.
Kuze, C. Makochekanwa, M. Hoshino, M. Oura
Phys. Rev. A 71, 052704 (2005).
X-J. Xiu, G. Prümper, K.Ueda et al. Phys. Rev. A
(to be published)
G. Prümper, X-J. Xiu, K.Ueda et al. to be
published
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Future prospects for gas-phase science (AMO and
photochemistry) with 4GLS
1. Femtosecond time-resolved photoelectron
spectroscopy probing evolution of the charge
redistributions via a change of molecular
conformation
2. Coherent control using coherent-phase double
pulses - a proposal for installation of the
interferometer in the UV/VUV beamline
3. Femtosecond time-resolved pump-probe
experiments for coherent controlled wave-packets
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The end
Thank you very much for your attention!