IR Studies of NH3, Pyridine, CO, and NO Adsorbed on Transition Metal Oxides

Abstract

Chemisorption of small molecules is often used as a probe for By probing the surface properties of transition metal oxides. the interaction of molecules with the surface, information is often obtained on the oxidation state, the coordination symmetry, the degree of coordination unsaturation of the surface cations, the acid-base properties of the surface hydroxyl groups, and the presence and the nature of surface Lewis acid and B rosnsted acid sites. This information is deduced from experimental measurements of the adsorption isotherms, the heats of adsorption, the thermal desorption spectra, and the vibrational spectra of the adsorbate. Until recently, when high resolution electron energy loss spectroscopy became available, vibrational spectra were obtained with infrared spectroscopy. Laser Raman spectroscopy has seldom been used because of the low Raman scattering cross section of most molecules.