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Molecular dynamics simulations of collision-induced desorption. I. Low coverage N2 on Ru,,001...

Summary: Molecular dynamics simulations of collision-induced desorption. I. Low
coverage N2 on Ru,,001...
Leonid Romm and Micha Asscher
Department of Physical Chemistry and Farkas Center for Light Induced Processes, The Hebrew University,
Jerusalem, 991904, Israel
Yehuda Zeiri
Department of Chemistry, Nuclear Research Center, Negev, P.O. Box 9001, Beer-Sheva, Israel
Received 21 July 1998; accepted 5 November 1998
Classical molecular dynamics simulations have been performed to study the details of
collision-induced desorption CID of nitrogen molecules adsorbed at low coverages on Ru 001 .
Semiempirical potential energy surfaces PES were used to describe the movable two layers of 56
ruthenium metal atoms each, the nitrogen adsorbate, the Ar and Kr colliders, and the interactions
between them. An experimentally measured threshold energy for the CID process of 0.5 eV and the
dependence of the cross section des on incidence energy and angle of incidence have been precisely
reproduced in the energy range of 0.52.5 eV. Strong enhancement of the des is predicted as the
angle of incidence increases. Kinetic energy and angular distributions of the scattered rare gas and
the desorbing nitrogen were determined as a function of the dynamical variables of the collider. It
is predicted that half of the collision energy is transferred to the solid and the other half is shared
among the two scattered species. While no vibrational excitation is observed, efficient rotational
energy excitation is predicted which depends on both incident energy and angle of incidence. Polar


Source: Asscher, Micha - Institute of Chemistry, Hebrew University of Jerusalem


Collections: Chemistry