Rostock 2019 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 8: XUV and X-ray Excitation and Spectroscopy
MO 8.2: Vortrag
Montag, 11. März 2019, 16:30–16:45, S HS 001 Biologie
Delayed relaxation of highly excited cationic states in naphthalene — Geert Reitsma1, Johan Hummert1, Judith Dura1, Vincent Loriot2, Marc J. J. Vrakking1, Franck Lépine2, and •Oleg Kornilov1 — 1Max Born Institute, Berlin, Germany — 2Institut Lumière Matière, Université Lyon 1, CNRS, France
The efficiency of energy transfer in ultrafast electronic relaxation of molecules depends strongly on the complex interplay between electronic and nuclear motion. Modern tools of time-resolved spectroscopy allow investigation of these processes in "real" time. In this study we report two-color pump-probe experiments that probe the relaxation dynamics of highly excited cationic states of naphthalene, a prototypical polycyclic aromatic hydrocarbon molecule. The cations are produced using wavelength-selected, ultrashort extreme ultraviolet pulses and probed by subsequent ionization with a moderately-strong NIR pulses. Surprisingly, the observed relaxation lifetimes increase with the cationic excitation energy. We postulate that the observed effect is the result of a quantum mechanical population trapping that leads to delayed relaxation of molecules in the regions with high density of excited states. Comparison with previous results on relaxation dynamics of larger polyaromatic hydrocarbons suggests that this may be a general phenomenon in relaxation of PAH molecules.