AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeA

Paper SS2-WeA10
Desorption Kinetics of Hydrogen and Deuterium from Diamond (111)x(1x1) via Helium Atom Scattering

Wednesday, November 4, 1998, 5:00 pm, Room 309

Session: Photochemistry and Deposition
Presenter: S.A. Safron, Florida State University
Authors: S.A. Safron, Florida State University
J.G. Skofronick, Florida State University
A. Glebov, Max Planck Institut fuer Stroemungsforschung, Germany
J.P. Toennies, Max Planck Institut fuer Stroemungsforschung, Germany
S. Vollmer, Max Planck Institut fuer Stroemungsforschung, Germany
Correspondent: Click to Email
The rate constants for the isothermal desorption of hydrogen and deuterium from diamond (111)-H(1x1) and -D(1x1) surfaces, respectively, have been measured over the temperature range 990 K to 1080 K by monitoring the helium atom Bragg diffraction beam intensities as a function of time. The rate behavior for both H and D followed first order reaction kinetics and a distinct isotope effect was observed in the desorption rates. The temperature dependence of the rate constants could be represented by an Arrhenius law. In fitting the data to determine the Arrhenius activation energies, the pre-exponential (or frequency) factors were taken to be the previously reported diamond (111)-(1x1) C-H or C-D stretching mode (S-mode) frequencies, 8.5x10@super13@ s@super-1@ for H and 6.4x10@super13@ s@super-1@ for D. The respective activation energies were then determined to be 2.69 eV (62.0 kcal/mol) and 2.74 eV (63.2 kcal/mol).@footnote1@ @FootnoteText@ @footnote1@ Work supported in part by US DOE grant no. DE-FG02-97ER45635 and NATO grant no. GRC.961145.