Raman Spectra of Adsorbed Molecules : Quenching of Fluorescence by Adsorption

Abstract

IT is well known that the infra-red spectra of molecules go through changes in position and intensity by their adsorption on solid surfaces^1–8. In earlier communications we have shown⁹ that the infra-red spectra of organic molecules spread in molecular layers over the surfaces of inorganic salts show differences in position and intensity of the bands compared with the spectra of the bulk substances. The observed differences are greater the more the atomic distances of the vibrating groups coincide with the lattice distances of the salt surfaces. The distortion of molecules with a centre of symmetry by the local fields of the lattice surface causes the appearances of Raman active vibrations in the infra-red.