Hamburg 2009 – scientific programme

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SYUF: Ultra-fast Dynamics in FEL Light Pulses

SYUF 1: SYUF I

SYUF 1.2: Invited Talk

Wednesday, March 4, 2009, 14:30–15:00, VMP 8 HS

Electronic decay in clusters and molecules subject to intense FEL radiation — •Vitali Averbukh, Ulf Saalmann, and Jan Michael Rost — Max Plank Institute for the Physics of Complex Systems, Dresden, Germany

Electronic decay sets in after ionization or excitation of an inner-shell electron by absorption of a high-energy photon, and can proceed by a wide variety of physical mechanisms leading to emission of secondary electrons on femto- or attosecond time scales. A distinctive feature of the interaction of molecules and clusters with intense FEL pulses is the capability of the FEL to promote the target system into a highly ionized state well within the pulse duration. Practically, this means that the electronic decay processes induced by the FEL radiation occur in a highly charged environment. In this presentation, I will review our recent theoretical work on the effect of the charged environment on the intra- and inter-atomic decay processes in clusters and molecules. It will be shown that the presence of a neighboring charge can affect the decay rates, sometimes daramatically, through the distortion of atomic orbitals involved in the non-radiative electronic transitions. Moreover, it will be argued that for the processes leading to emission of relatively slow secondary electrons, the mere concept of the exponential decay characterized by a rate may no longer be applicable because of the trapping of the emitted electrons by the neighboring charges.