AVS 49th International Symposium
    Surface Science Monday Sessions
       Session SS2-MoM

Paper SS2-MoM4
Adsorption and Desorption of Methanol on WO@sub 3@ (100) Surfaces

Monday, November 4, 2002, 9:20 am, Room C-112C

Session: Oxide Structure and Surface Chemistry
Presenter: S. Ma, University of Maine
Authors: S. Ma, University of Maine
F.G. Amar, University of Maine
B.G. Frederick, University of Maine
Correspondent: Click to Email
We have investigated the role of intermolecular interactions, surface site heterogeneity, and surface diffusion during the desorption of methanol from the oxidized and reduced surfaces of (100) oriented, epitaxially grown WO@sub 3@ films on Al@sub 2@O@sub 3@(1-102) substrates. Ultra-violet photoelectron spectroscopy (UPS) showed that methanol adsorbed molecularly on the oxidized WO@sub 3@ surface but dissociatively on the reduced surface. On both surfaces, calibrated thermal desorption spectroscopy (CTDS) showed desorption of methanol in an asymmetric peak which shifts to lower temperature with increasing coverage, typical of water and alcohols on other oxide surfaces. X-ray photoelectron spectroscopy (XPS) was used to characterize the surface by monitoring the W4f and valence band region, while separate STM studies indicate that the surface is heavily stepped. Monte Carlo simulations indicate that surface heterogeneity and rapid diffusion are consistent with the observed desorption spectra. By contrast, simulations on a homogeneous surface require repulsive intermolecular interactions, which is inconsistent with hydrogen bonding.