Mainz 2017 – scientific programme
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A: Fachverband Atomphysik
A 3: XUV/X-ray spectroscopy I
A 3.3: Talk
Monday, March 6, 2017, 15:15–15:30, N 2
Site-selective x-ray photofragmentation of molecules — •Ludger inhester1, Sang-Kil Son1, and Robin Santra2 — 1Center for Free-Electron Laser Science, DESY, Hamburg — 2Department of Physics, University Hamburg
For understanding the impact of radiation damage in biological processes it is important to know how a molecule fragments after x-ray absorption. After x-ray ionization of a core electron and subsequent Auger decay the molecular electronic structure is left in a two-valence hole configuration. This two-valence hole configuration typically initiates molecular dissociation. In contrast to the core electron, the valence holes are often delocalized over large parts of the molecule. Thus, ionization on a specific atomic site may lead to disruption of the molecule at remote parts, which makes it difficult to predict into which fragments the molecule breaks apart. Because of the large number of accessible two-hole configurations the quantitative theoretical prediction of molecular fragments is a challenging task.
We address this issue using our newly developed XMOLECULE toolkit(Y. Hao et al., Struct. Dyn. 2 (2015) 041707, L. Inhester et al., Phys. Rev. A, 94 (2016) 023422). Based on calculated Auger transition rates and Mayer's bond order analysis, we present a way to efficiently calculate the molecular fragments after x-ray absorption. Results for ethyl trifluoroacetate (CF3-CO-O-CH2-CH3, a.k.a the Siegbahn or the ESCA molecule) are compared with recent experiments. With these results we demonstrate that the abundance of certain molecular fragments is specific for x-ray ionization on a particular atomic site.