Angular distributions of desorbing N2 in thermal N2O decomposition on Rh(100)

The angular distribution of desorbing N-2 was studied in the decomposition of N2O(a) on Rh(100) at 60-140 K by means of angle-resolved temperature-programmed desorption. N-2 desorption shows two peaks at around 80 K and 110 K. At low N2O coverage, the former collimates far from the surface normal toward the [0 0 1] direction, whereas at high coverage, the desorption sharply collimates along the surface normal. The adsorption form of N2O and its dissociation were also examined by DFT-GGA calculations. Dissociating N2O is proposed to be lying along the [0 0 1] direction at low coverage and to change to an upright form bonding through the terminal oxygen at high coverage. (C) 2007 Elsevier B.V. All rights reserved.