PROBING THE SURFACE-ACIDITY OF SINGLE-CRYSTAL ALUMINA SURFACES - CO ADSORPTION AS MEASURED BY INFRARED REFLECTION-ABSORPTION SPECTROSCOPY

For the first time infrared reflection absorption spectroscopy (IRAS) was applied to the study of adsorbates on single crystal aluminum oxid e (alumina) surfaces. The adsorption of CO on amorphous as well as the gamma, theta and alpha phases of thin alumina films prepared on a NiA l(001) crystal was investigated. CO adsorption occurred on ail phases of alumina except for gamma-Al2O3. Temperature programmed desorption ( TPD) confirmed this. The CO stretch frequency was found to increase as a function of increasing surface coverage. The CO stretch frequency d ecreased with the higher temperature phases, indicating increased inte raction between adsorbate and substrate. There was no observable chemi cal reaction or dissociation associated with the adsorption of CO on a lumina. (C) 1998 Elsevier Science B.V. All rights reserved.