The results are important for modeling the kinetic aspects of chemical vapor deposition and etching for electronic device fabrication. Through the use of molecular dynamics simulations, we are investigating the various mechanisms of surface diffusion and the effects of such mechanisms in surface diffusion-limited chemical reactions. We are also developing a general quantitative model relating surface diffusion coefficients to bimolecular surface reaction rate constants. Based on ultrahigh-vacuum kinetic studies, we have developed a quantitative predictive model for growth, and have confirmed potential growth conditions in real deposition experiments. This work represents the first such optimization performed based on fundamental kinetic surface studies in any adsorption system of practical interest.
Work now focuses on bringing the process into suitable form for large-scale production.
The reaction network describing tropospheric pollution chemistry has until now been thought to involve only homogeneous gas-gas interactions, with solids serving merely as sinks for condensible species. We are showing quantitatively for the first time that in fact reactions of gases with suspended particulates can contribute substantially to this network. We are looking with laboratory reactors at the oxidation of simple ubiquitous alcohols to aldehydes on fly ash where the heterogeneous mechanism dominates the homogeneous, with implications for acid rain and atmospheric carcinogens. I n this investigation we examine the flow properties of weakly flocculated suspensions. A model system has been chosen in which, by altering temperature, the suspension can be reversibly gelled.