ADSORPTION AND DISSOCIATION DYNAMICS OF H-2 AND N-2 ON CU(111) STUDIED BY GLANCING INCIDENCE ENERGETIC BEAM SCATTERING TECHNIQUES

Abstract

We seek to investigate the topography of molecule-surface potential energy surfaces, in particular the existence and role of precursors to dissociation and the nature of barriers to dissociation, using glancing incidence energetic beam scattering techniques. Highly collimated pulsed beams of H2+ and N2+ were scattered from an ion beam polished Cu(111) surface. The flight-time distributions of scattered molecular and atomic products were recorded as a function of incidence angle of the beam to the surface, azimuthal orientation of the crystal, scattering angle, and incident beam energy. The dissociation products H and N exhibit regularly spaced fine structure peaks in their kinetic energy distributions. Such fine structure could in principle arise from vibrational structure in a molecular intermediate to dissociation, from transient adsorption or skipping motion of the beam on the surface, or from a quantum mechanical interference effect. The data tends to support the latter interpretation.