Lateral Interaction between Molecules Adsorbed on the Surfaces of Non-Metals

Spectral manifestations of lateral interactions between molecules adsorbed on non-metallic adsorbents, mostly oxides are considered. Static interaction, repulsive or attractive can be distinguished from the dynamic or resonance dipole–dipole interaction (RDDI) by means of isotopic dilution. Analysis of spectral data on CO adsorbed at low temperatures on ZnO, some other oxides or halogenides as well as recent quantum chemical calculations shows that static effect is enhanced by the solid due to the effect of surface relaxation induced by adsorption. Computer modelling of static and dynamic interactions enable one to explain the structure of the bands of adsorbed CO, frequency shifts, and other details in the spectra. Attractive interactions between different molecules can lead to mutual enhancement of adsorption and to the phenomena of induced Brønsted acidity and basicity, or the superacidity of some oxides exposed to gaseous acids. The theory and new experimental data on the influence of RDDI on the band shape of adsorbed SF6 and CF4 are discussed. Spectral evidence for RDDI and vibrational energy transfer between NF3 and pre-adsorbed SF6 on ZnO is reported.