Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 57: Surface Chemical Reactions and Heterogeneous Catalysis II

O 57.9: Vortrag

Donnerstag, 29. März 2007, 17:45–18:00, H38

H laserdesorption experiments from HOPG with VUV photonenergies at the FLASH facility in Hamburg — •Carsten Thewes, Björn Siemer, Tim Hoger, and Marco Rutkowski — Physikalisches Institut, Westfälische Wilhelms-Universität, 48149 Münster

During the past years, the understanding of the interaction of atomic and molecular hydrogen with carbon surfaces has gained new attention for the fields of hydrogen storage [19 and molecular hydrogen formation in the interstellar medium [2, 3]. Our recent experiments concerning the desorption of H and D atoms adsorbed on highly oriented pyrolytic graphite (HOPG) will be surveyed. The experiments are performed at the Free Electron Laser facility FLASH at DESY using 32.5 nm XUV photons. The recording of arrival time distributions via a delayable laser detection scheme (hydrogen 2s ← 1s excitation REMPI process), information about possible reaction mechanisms is accessible. Based on this background an insight to the so far evaluated data and results will be given. The analysis of the kinetic energy distribution of the desorbing neutral hydrogen atoms reveals different contributions peaking at around 2, 8 and 25 meV. The new experimental data is discussed in the model of Hammer et al. [3]. [1] L. Schlapbach, A. Züttel, Nature 414, 353 (2001) [2] N.Rougeau, D. Teillet-Billy and V. Sidis, Chem. Phys. Let., 431, 135138 (2006) [3] L. Hornekær, E. Rauls, W. Xu, Z. Sljivančanin, R. Otero, I. Stensgaard, E. Lægsgaard, B. Hammer, F. Besenbacher, Phys. Rev. Let. 97 (18), 186102 (2006)