Erlangen 2018 – scientific programme
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A: Fachverband Atomphysik
A 18: Ultrafast Spectroscopy with XUV (joint session MO/A)
A 18.2: Talk
Monday, March 5, 2018, 16:45–17:00, PA 2.150
A chemical understanding of the lack of site-specificity in molecular inner-shell photofragmentation — •Ludger Inhester1,2, Bart Oostenrijk3, Sang-Kil Son1,2, Robin Santra1,2,4, Linda Young5, and Stacey L. Sorensen3 — 1Center for Free-Electron Laser Science, DESY — 2The Hamburg Centre for Ultrafast Imaging — 3Department of Physics, Lund University — 4Department of Physics, University of Hamburg — 5Argonne National Laboratory
In many cases fragmentation of molecules upon inner-shell ionization is very unspecific with respect to the initially localized ionization site. Often this finding is interpreted in terms of an equilibration of internal energy into vibrational degrees of freedom after Auger decay. Here we investigate the x-ray photofragmentation of ethyl trifluoroacetate upon core electron ionization at environmentally distinct carbon sites using photoelectron-photoion-photoion coincidence measurements and ab-initio electronic structure calculations. For all the 4 carbon ionization sites, the Auger decay weakens the same bonds and transfers the two charges to opposite ends of the molecule, which leads to a rapid dissociation into 3 fragments followed by further fragmentation steps. The lack of site-specificity is attributed to the character of the dicationic electronic states after Auger decay, instead of a fast equilibration of internal energy.