Ursula Keller wins “Swiss Nobel” Marcel Benoist Prize
Farewell: the NCCR MUST ended 
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Unusual keynote talk at an international scientific conference
NCCR MUST at Scientifica 2021Attosecond delays in photoionization
| Date | Mo, 06.05.2013 | |
| Time | 16:45 | |
| Speaker | Alfred Maquet, Laboratoire de Chimie Physique-Matière et Rayonnement, Université Pierre et Marie Curie, Paris Cedex, France | |
| Location | ETH Zurich, Hönggerberg Campus, HPF G-6 | |
| Program | Attosecond delays in photoionization Abstract: Whether time is a parameter or an operator in Quantum Mechanics is a long-standing question since the foundation of the theory. In short, the question remains to decide if time is a parameter (as in classical mechanics) or a measurable quantity associated to a hermitian operator expressed in terms of dynamical variables. For years, the question was considered as being academic and it attracted mainly the specialists' attention. Things have changed, first in the 1980s, in parallel with the advent of Scanning Tunnelling Microscopy (STM) devices. The related concept was the one of defining a "Tunnelling Time", or in other words of how measuring "the time it takes a particle to tunnel through a potential barrier"? It turns out that no consensus has been reached yet on how to define such tunnelling times. Another viewpoint has emerged in the 2010s, with the advent of sources delivering "attosecond" (1 as = 10-18 s) pulses of coherent XUV radiation. This has made feasible to investigate photoionization in the time domain via “two-colour” IR-XUV schemes that have opened the possibility to "clock" the primary photoionization process on the natural time-scale governing electronic motion. We shall address some issues raised by this latter generation of measurements, which have evidenced the existence of attosecond time delays between the emission times of electrons ejected from different sub-shells in atoms, upon the absorption of one XUV photon [1-2]. Also, we shall summarize the results of a theoretical analysis [3] of the experiments reported in [2]. [1] M. Schultze et al. "Delay in Photoemission", Science 328 1658-1662 (2010). [2] K. Klünder et al. "Probing Single-Photon Ionization on the Attosecond Time Scale", Phys. Rev. Lett. 106, 143002 (2011). [3] J.M. Dahlström et al. “Theory of attosecond delays in laser-assisted photoionization”, Chemical Physics 414, 53-64 (2013) Host: Ursula Keller, Ultrafast Laser Physics, IQE |
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