AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS1+MC-WeA

Paper SS1+MC-WeA4
Low Temperature Microcalorimetric Heats of Adsorption and Sticking Probabilities of Metals on Oxide Surfaces

Wednesday, October 4, 2000, 3:00 pm, Room 208

Session: Oxide Surfaces, Interfaces and Defects
Presenter: D.E. Starr, University of Washington
Authors: D.E. Starr, University of Washington
C.T. Campbell, University of Washington
Correspondent: Click to Email
Single crystal adsorption microcalorimetry is a powerful method to study the heats of adsorption of gaseous atoms or molecules onto single crystal surfaces. The technique has been utilized to study the energetics of metal film growth from the initial stages of growth through the multilayer regime. Results for metal deposition onto metal oxide substrates all indicate an initial heat of adsorption much lower than the bulk heat of sublimation of the metal. This indicates a weaker interaction of the metal atoms with the substrate than with themselves, providing insights into the energetic driving force for the three dimensional islanding of the metal film in the submonolayer regime. Recent advances in this technique has allowed the first low temperature measurements (~ 160 K) to be performed. Low temperature results for the deposition of Pb onto a MgO(100) thin film grown on Mo(100) will be presented. These measurements have similar sensitivities to room temperature measurements. The changes in the heat of adsorption versus coverage from room temperature measurements to low temperature result from the kinetic factors governing the film morphology. In conjunction with the calorimetric measurements, the metals sticking probability as a function of coverage at a variety of temperatures allows kinetic parameters to be extracted from the model fit to the sticking probability curves. This results in deeper insights into the microcalorimetrically measured heats of adsorption.