4GLS users meeting July 4 2005, Daresbury Laboratory, United Kingdom

1. 4GLS users meeting July 4 2005, Daresbury Laboratory, United Kingdom My task is to give ashort presentation describing examples of experiments enabled by 4GLS and not feasible with 3rd Generation Light Source like SPring-8. Kiyoshi Ueda and Georg Prümper Studying and controlling ultrafast phenomena in atoms and molecules - Our proposal for the experiments with 4GLS - Inst. Multidisciplinary Research for Advanced Materials, Tohoku University, Japan

2. 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

3. “Conventional” time-resolved pump-probe measurement for vibrational motion in I2 molecules Introduction – time-resolved Zewail’s Femtochemistry in 1990s Femtosecond time-resolved pump-probe experiments made a nuclear motion of a molecular system visible. Intensity(arb.) Revisit to Zewail’s Novel prize experiment.

4. One-step beyond “Femtochemistry on nuclear motions” is: Femtoseond time-resolved PES 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!

5. 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 don’t 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 don’t we install in 4GLS an interferometer for making phase-coherent double pulses for coherent control ?

6. l0 Splitting one pulse into two pulses with time delay EXPERIMENTAL CHAMBER Photon beam from 4GLS (FT limit coherent pulse)

7. Time independent picture 7.43 7.39 7.41 v=4 v=4 v=3 v=3 v=5 v=5 l0 :adjusted to the electronic transition. Frequency comb is made by the interferometer. Let’s irradiate the molecule with this light ! 2 2 Vibronic excitation takes place ! No excitation takes place ! d=nl0 1 1 d=(n+0.5) l0 0 0 7.43 7.39 7.41 Angular Frequency (fs-1) Angular Frequency (fs-1)

8. 0.44 0.44 tpump=Tvib 0.36 0.36 0.28 0.28 tpump=Tvib+p/wLaser Distance tpumpTvib 4 5 1 2 3 0 Time Time dependent picture Tvib:vibrational period

9. Experimental scheme and pump-probe setup for the wave-packet interferometry APM: Omori et al. PRL 91, 243003 (2003)

10. 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 !

11. 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.

12. 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

13. Location of SPring-8

14. SPring-8 view from sky BL27SU : “state-of-the-art” soft X-ray beamline

15. Doppler effect Blue shift Red shift F* e- (wave) E Ultra-fast dissociation of core-excited molecules Case study: SF6 F1s-1s* • resonant inner shell excitation • F 1s -> 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

16. F* e- (wave) E Dissociation dynamics probed by Doppler effects as a function of detuning Controlling ultrafast dissociation by de-tuning fast slow The fragmentation speed changes as a function of detuning. SF6 F 1s ->sS-F*

17. Doppler profile analysis Parallel (0 deg) Perp. (90 deg) 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.

18. Message: this detuning experiment gives the information equivalent with time resolved photoemission spectroscopy!

19. Coincidence experiment Momentum correlation Coincidence map: x-axis electron energy y-axis ion momentum The electron shift tells us the momentumof the emitter!

20. late ion blue early ion red late ion red F ion CF3 fragment 5 % Acceleration of F is faster than Auger-decay. The coincidence data for CF4 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!

21. Anisotropic ultrafast dissociation probed by the Doppler effect in resonant photoemission from CF4 Credits 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 -> 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

22. 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

23. The end Thank you very much for your attention!