Interpretation of the infra-red spectra of CO adsorbed on evaporated alkali metal halides

Abstract

Gevirzman and Kozirovski observed that the C—O stretching band for CO adsorbed on evaporated alkali metal halide films at 77 K frequently appears as a doublet, with a splitting of about 10 cm^–1. It is shown here that their data may be accounted for quantitatively using the optical equations derived by Dignam, Rao and Roth. On this basis, the splitting of the C—O band arises predominantly as a result of a local field effect, the planar array of adsorbed CO molecules providing a local unaxial symmetry.