DISSOCIATIVE SCATTERING OF FAST H-2 AND N-2 FROM PT(111) UNDER GLANCING ANGLES OF INCIDENCE

We have scattered fast beams of neutral H-2 and N-2 molecules from Pt( 111) under glancing angles of incidence. By directly measuring the rel ative velocity of the dissociation fragments of those molecules which dissociatively scatter, we obtain distributions of the kinetic energy in the centre of mass of the fragments as a function of the final orie ntation of the internuclear coordinate. The distributions are qualitat ively similar to those obtained earlier for H-2 and N-2 scattering fro m Cu(111) [Surf. Sci. 307-309 (1994) 147]. The results are consistent with a dissociative scattering mechanism involving multiple Franck-Con don transitions between electronic states of the molecule-metal system .