Regensburg 2007 – scientific programme
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O: Fachverband Oberflächenphysik
O 32: Semiconductor Substrates
O 32.3: Talk
Tuesday, March 27, 2007, 16:15–16:30, H39
High energy femtosecond UV photo desorption dynamics of NO from HOPG at FLASH — •Tim Hoger1, Björn Siemer1, Carsten Thewes1, Marco Rutkowski1, Helmut Zacharias1, Stefan Düsterer2, and Rolf Treusch2 — 1Universität Münster, Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster — 2DESY, Hasylab, Notkestr. 85, 22603 Hamburg
The interaction of nitric oxide under high energy irradiation is an important issue in understanding the heating of the atmosphere and the formation of acid rain. At low temperatures NO adsorbs on dust grains or Mi particles. We present recent results of the interaction of NO adsorbed on graphite with high energy radiation. The desorption is achieved by the free electron laser at Hamburg (FLASH) supplying femtosecond pulses of up to 100 µJ with a photon energy of 57 eV. All internal energies of NO molecules desorbing from a highly oriented pyrolytic graphite (HOPG) sample are resolved in a pump-probe experiment. Highly excited molecules with a vibrational temperature around Tvib ≈ 2500 K and a high rotational excitation up to Trot≈ 1200 K are detected. Possible excitation and desorption mechanisms in this high energy regime are discussed.