CO adsorption on the Pd(110)c(2 × 4)-O surface — formation of a p(2 × 4) structure

Abstract

The CO adsorption on the Pd(110)c(2 × 4)-O surface at 90 K has been investigated by using high resolution electron energy loss spectroscopy (EELS), low-energy electron diffraction (LEED), and thermal desorption spectroscopy (TDS). Three adsorbed states of CO have been found which are characterized by the CO stretch energies 235–237, 250–253 and 261–267 meV. It is proposed that CO molecules associated with these CO stretch energies are adsorbed in the “O-free” long-bridge sites, the “O-coordinated” long-bridge sites and the on-top sites of the c(2 × 4)-O structure, respectively. The CO adsorption induces the formation of a p(2 × 4) structure, which is completed by the formation of a Pd(110)p(2 × 4)-(8CO + 4O) structure at the saturation coverage ( ϑ co = 1). The structure model of the p(2 × 4)-(8CO + 4O) surface is discussed.