AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP1
Studies of Hydrogen on Pd{111} at 4 K Utilizing Scanning Tunneling Microscopy and Spectroscopy

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: L.C. Fernández-Torres, The Pennsylvania State University
Authors: L.C. Fernández-Torres, The Pennsylvania State University
E.C.H. Sykes, The Pennsylvania State University
P. Han, The Pennsylvania State University
S.U. Nanayakkara, The Pennsylvania State University
P.S. Weiss, The Pennsylvania State University
Correspondent: Click to Email
The interaction of hydrogen with Pd{111} has been investigated with low temperature scanning tunneling microscopy and spectroscopy. Palladium is unique in its ability to both adsorb and absorb hydrogen. Adsorption of low exposures of hydrogen has allowed for the observation of tip-induced hydrogen atom diffusion at 4 K. The diffusion of atomic hydrogen at 4 K has been ascribed to inelastic tunneling of electrons; inelastic electron tunneling spectroscopy (IETS) corroborates this assignment, and the hydrogen atom diffusion barrier has been determined. Adsorption of high exposures of hydrogen results in formation of two ordered overlayer structures: (1x1)-H and (@sr@3x@sr@3)-2H. Absorption of hydrogen into subsurface sites in Pd, concurrent with H diffusion from the bulk, have been attributed as the predominant reasons for two observed phenomena: tip-induced vacancy ordering, and Pd{111} lattice distortion.