An infra-red study of CO adsorption on potassium-doped pt(110)-(1 × 2); the long range potassium-CO interaction

Abstract

The co-adsorption of CO with very low coverages of potassium on Pt(110)-(1 × 2) has been studied using RAIRS, LEED and TPD. Low coverages of potassium (q K < 0.1) very slightly increase the CO desorption temperature but lowers the vibrational frequency of the linear CO species by 100 cm −1 . The v(CO) peak on the potassium doped surface is also significantly broader (FWHM of 40 cm −1 ) than that of the clean surface (FWHM of 18 cm −1). The perturbed CO species on the potassium doped surface exhibits a coverage dependent frequency shift identical in magnitude to that of CO on the clean Pt(110) surface. Isotope mixture experiments indicate that the upward frequency shift with CO coverage is due solely to dipole-dipole interactions. No additional chemical contribution to the coverage dependent frequency shift is induced by the presence of potassium, despite the, downward shift in the singleton frequency for the linear CO species of 100 cm −1.