Mainz 2017 – scientific programme
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MO: Fachverband Molekülphysik
MO 10: Highly Excited Molecules and Clusters
MO 10.6: Talk
Wednesday, March 8, 2017, 16:00–16:15, N 6
Comparing UV and strong-field induced dynamics in selenophene probed by femtosecond XUV transient absorption spectroscopy — •Florian Lackner1,2,3, Adam S. Chatterley1,2, C. D. Pemmaraju1,4, Kristina D. Closser4, David Prendergast4, Daniel M. Neumark1,2, Stephen R. Leone1,2,5, and Oliver Gessner1 — 1Chemical Sciences Division, Lawrence Berkeley National Lab — 2Department of Chemistry, UC Berkeley — 3Institute of Experimental Physics, TU Graz — 4The Molecular Foundry, Lawrence Berkeley National Lab — 5Department of Physics, UC Berkeley
UV and strong-field induced dynamics in selenophene (C4H4Se) molecules are studied by femtosecond transient inner-shell absorption spectroscopy at the Se 3d edge. Spectra obtained upon strong-field ionization are dominated by emerging bare Se ions produced in a sequential two-step mechanism, whereby the initial ring-opening and the subsequent fragmentation are associated with two characteristic time-scales of τ1 ≈ τ2 ≈ 80 fs. In contrast, excitation with a moderately intense UV (266 nm) pump pulse gives predominantly rise to the formation of bare Se atoms and a smaller contribution of Se ions. The ionic contribution increases with UV intensity. In both cases, spectral signatures of stable molecular products are found as well, which are assigned based on TDDFT calculations. Independent of the excitation/ionization scheme, the braking of both C-Se bonds is the dominant relaxation channel in selenophene, which can be traced in real-time by XUV transient absorption spectroscopy.