Angular distributions in stimulated desorption: Photodesorption of ammonia from a Cu(111) surface
T. Hertel, M. Wolf, and G. Ertl
Chem. Phys. Lett. 257, 155 (1996).
The angular distributions of flux and mean translational energy in the stimulated desorption of neutral particles contain valuable information about the influence of substrate corrugation on the desorption dynamics. We present a simple model which predicts angular distributions if the particle momentum parallel to the surface is conserved during the desorption process. The model allows to calculate the temperature dependence of angular distributions and the observed decrease of translational energy with increasing angle of desorption. For the photostimulated desorption of NH3 from Cu(111) at two sample temperatures our analysis shows that substrate corrugation has no significant influence on the photodesorption dynamics and that angular flux distributions are essentially broadened by thermal motions of the molecules within the surface plane, i.e. due to the frustrated translation.
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