The orientation of CO at the step sites of the Pt(321) surface and its implications for catalytic oxidation

Abstract

Angle-resolved photoemission spectroscopy employing polarized He II(40.8 eV) radiation has been used to characterize two distinct types of CO bonding, associated with terrace and step sites, that were shown to exist on the Pt(321) surface in an earlier TDS study. CO was found to be oriented normal to the (111) terraces of Pt(321) as it is to Pt(111). The step site CO was found to be oriented asymmetrically with respect to the Pt(321) normal and to be 40°±20° from [321] in the direction of [214]. This existence of such a tilted CO orientation has been postulated to explain the dynamics of the CO oxidation reaction on Pt surfaces in several recent studies. © 1984 American Institute of Physics.