Surface temperature effects in dynamic trapping mediated adsorption of light molecules on metal surfaces: H2 on Pd(111) and Pd(110).

H.F. BUSNENGO, M. A. DI CÉSARE, W. DONG Y A. SALIN

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Año: 2005 vol. 72 p. 125411 - 125419

0163-1829

We perform classical trajectory calculations on nonactivated H2 dissociative adsorption on Pd surfaces, using the surface oscillator model to account for phonons. We show that the role of surface temperature is closely related to the dynamic trapping process that enhances energy exchange with the surface by increasing considerably the interaction time before dissociation or reflection. Correlatively, the trapping process itself is enhanced by energy loss to the surface while it is quenched by energy gain. We show that, for a hot surface, isotopic effects in temperature dependencies are driven by the enhanced interaction time when the mass increases for a given energy and not by the ratio of molecule mass to that of surface atoms. Finally, we find that introduction of energy dissipation toward the bulk through generalized Langevin oscillators gives rise to molecular adsorption.