AVS 45th International Symposium
    Surface Science Division Monday Sessions
       Session SS2-MoA

Paper SS2-MoA4
Studies of Oxygen Species on a Heated Silver Membrane

Monday, November 2, 1998, 3:00 pm, Room 309

Session: Surface Chemistry on Model Catalysts
Presenter: R.J. Beuhler, Brookhaven National Laboratory
Authors: R.J. Beuhler, Brookhaven National Laboratory
R.M. Rao, Brookhaven National Laboratory
M.G. White, Brookhaven National Laboratory
Correspondent: Click to Email
Oxidation reactions catalyzed by silver are a multi billion dollar enterprise worldwide. Such reactions have been investigated extensively by conventional surface science techniques, however, applications using state- or species-selective laser techniques are difficult to carry out for practical reasons specific to Ag surfaces. For example, the dissociative adsorption cross section of O@sub 2@ on Ag is on the order of 10@super -4@, which means that the high pressure of O@sub 2@ impinging on a silver surface makes state-selective detection of reaction products under collision free conditions nearly impossible. As a step towards understanding of the dynamics of oxidation reactions on Ag, we have undertaken a study of the oxygen species and reactions on the high vacuum side of a heated silver membrane. High surface coverages of O-atoms are produced by dissociative adsorption of molecular oxygen on the high-pressure side of a heated Ag-foil through which the O-atoms diffuse to the surface. Reactions at the high vacuum side can be studied under conditions that allow energy and spectroscopic analysis of the products. Preliminary results have been obtained for the recombination reaction O@sub (a)@ + O@sub (a)@ = O@sub 2(g)@ using (2+1) REMPI laser spectroscopy to probe state and energy distributions of the desorbing molecules. Initial measurements on the yield and temperature dependence of the oxidation reactions of CO and ethylene at intermediate pressures (10@super -5@-10@super -4@ Torr) have also been performed. These results and limitations in the foil experiment will be discussed.