Sticking and scattering in the molecular chemisorption regime: CO on Pt(111)

Abstract

The nondissociative sticking of CO on Pt( 111 ) has been measured as a function of incident energy and angle. Both these sticking measurements and prior molecular beam scattering experiments are incompatible with simple theoretical models that describe successfully weak physisorption interactions. For strong chemical interactions, such as for CO-Pt ( 111), lateral and rotational corrugations in the interaction potential are large and play an important role in the scattering and sticking. Both translational to rotational and normal to parallel energy conversions cause substantial energy scrambling in the interaction. Classical trajectory calculations that incorporate these effects realistically predict a rather gentle fall off in sticking with incident energy, a scaling of sticking with total rather than normal energy and directly scattered distributions which consist of broad lobular components about the specular superimposed on an even broader diffuse component. All of these findings are in accord with experiment. © 1989 American Institute of Physics.