Mainz 2017 – scientific programme
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A: Fachverband Atomphysik
A 10: Diffraction and Coherences (with MO)
A 10.5: Talk
Monday, March 6, 2017, 18:15–18:30, N 6
Electronic decoherence following photoionization: full quantum-dynamical treatment of the influence of nuclear motion — •Caroline Arnold1,2,3, Oriol Vendrell1,3,4, and Robin Santra1,2,3 — 1Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany — 2Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany — 3The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany — 4Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus, Denmark
Photoionization using attosecond pulses can lead to the formation of coherent superpositions of the electronic states of the parent ion. However, ultrafast electron ejection triggers not only electronic but also nuclear dynamics---leading to electronic decoherence, which is typically neglected on time scales up to tens of femtoseconds. We propose a full quantum-dynamical treatment of nuclear motion in an adiabatic framework, where nuclear wavepackets move on adiabatic potential energy surfaces expanded up to second order at the Franck-Condon point. We show that electronic decoherence is caused by the interplay of a large number of nuclear degrees of freedom and by the relative topology of the potential energy surfaces. Application to H2O, paraxylene, and phenylalanine shows that an initially coherent state evolves to an electronically mixed state within just a few femtoseconds. In these examples, it is not the fast vibrations involving hydrogen atoms, but rather slow vibrational modes that destroy electronic coherence.