Abstract

In spite of many reports on uv laser enhanced gas-solid interactions, especially on photoetching and vapor deposition of solid materials, mechanistic studies on well characterized surfaces remain relatively few. The questions of quantum yields, molecular selectivities, the energetics of dissociation, surface reaction pathways and desorption mechanisms need clear answers. On metal surfaces, extremely rapid electronic decay via electron-hole pairs and charge-transfers can occur. The outcome can be highly unpredictable. In order to better understand the basic photochemical and/or photothermal processes and their consequences on the surface chemistry, we have used CH₂I₂ molecules adsorbed on Al₂O₃, Al and Ag as model systems for investigating the photofragmentation, the reaction and the desorption behavior involving the electronic excitation of the adsorbate (1-3). The study has been extended to include NH₃, C₂H₄ as well as CH₂I₂ adsorbed on both Al and O₂-exposed Al surfaces. The new results are presented here.

© 1989 Optical Society of America