1. 学术报告 AttoClock on atomic and molecular hydrogen
报告人：Prof Anatoli Kheifets （中国科学院国际访问学者）
时 间：10月25日（星期四）15：00
地 点：M楼1017会议室
个人履历:
Prof Anatoli Kheifets is the group leader of Correlated Many-Particle Dynamics at the Research School of Physics of the Australian National University, Canberra. He holds a Wilhelm & Elise Heraeus Guest Professorship at Goethe University Frankfurt and a Visiting Scientist award from the CAS President at the WIPM. He is a Fellow of the American Physical Society and a board member of Nature's Scientific Reports
报告摘要：
Attosecond angular streaking (attoclock) attempts to relate the tilt angle of the photoelectron momentum distribution with the time the tunneling electron spends under the barrier (tunneling time) . The alternative interpretation is that this anglar tilt is wholly attributed to the photoelectron scattering in the Coulomb potential of the ionic core . While the earlier experiments on He leave some ambiguity in their interpretation because of the possible role of many-electron correlation, the recent experiment on the atomic hydrogen can only be interpreted in terms of the zero tunneling time.
The attoclock measurement on molecular hydrogen H2 brings some additional information. Firstly, the photoelectron angular tilt in the polarization plane depends on the molecular orientation. The width of the angular distribution is even more sensitive to the orientation and differs significantly between the atomic and molecular hydrogen in the parallel and perpendicular orientation of the molecular axis. The width is also decreasing rapidly when the attoclock reading is taken outside the polarization plane. This results can be interpreted within the saddle point method . 
More significantly, the molecular attoclock can be based on the nuclear fragment detection rather than photoelectron detection. The sum momentum of the photoelectron and the H+2 ion is zero and hence their angular distributions are pointing to the opposite directions. In the meantime, dissociative fragmentation of H+2 is always aligned with the major polarization axis of the elliptically polarized light. It acts like a compass hand whereas the photoelectron and H+2 distributions act like the attoclock hand. The angle between these hands always complements the electron attoclock angle to 90◦. This has been also confirmed experimentally .