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

Paper SS2-MoM5
Interaction of Co@sub 3@O@sub 4@ Single-Crystal Surfaces with Water

Monday, November 4, 2002, 9:40 am, Room C-112C

Session: Oxide Structure and Surface Chemistry
Presenter: M.A. Langell, University of Nebraska-Lincoln
Authors: M.A. Langell, University of Nebraska-Lincoln
D.A. Pugmire, University of Nebraska-Lincoln
W.H. McCarroll, Rider University
Correspondent: Click to Email
Vacuum-annealed and vacuum-cleaved Co@sub 3@ O@sub 4@ single-crystal substrates have been characterized using the UHV surface analytical techniques of Auger electron spectroscopy, x-ray photoelectron spectroscopy, low energy electron diffraction and high resolution electron energy loss spectroscopy. Particular emphasis in this study has been placed on the characterization of surface oxygen, which often shows complex photoemission structure from core oxygen states, and of the tetrahedral/octahedral site occupancy of cobalt surface cations as it relates to the defect character of the spinel surface. These well-defined surfaces are subsequently probed by adsorption of H@sub 2@O, both at low (@<=@10@super -6@ Torr) and high (1-10 Torr) water vapor pressures. Dissociative adsorption to produce surface hydroxyls is an important process for air-exposed oxides and this mechanism was found to occur upon water exposure for the Co@sub 3@O@sub 4@ surface under UHV conditions. However, hydroxylation was most readily observed for stoichiometric surfaces upon electron or thermal activation of the water adsorbate. These surface species will be compared to hydroxyls generated under high vacuum and atmospheric conditions.