AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuM

Paper SS2-TuM2
Observation of the Motion of Individual Lead-oxide Molecules on Reconstructed Au(111) Using Scanning Tunneling Microscopy

Tuesday, November 5, 2002, 8:40 am, Room C-110

Session: Diffusion & Growth on Metal Surfaces
Presenter: A.J. Slavin, Trent University, Canada
Authors: M.C. Robinson, Trent University, Canada
A.J. Slavin, Trent University, Canada
Correspondent: Click to Email
Ultra-thin metal oxides are of great technological importance, so it is necessary to understand how these films grow, beginning at the molecular level. In this study we have used scanning tunneling microscopy (STM) to observe the room-temperature diffusion of lead-oxide molecules, most probably PbO, on the reconstructed Au(111) surface at coverages below 0.06 monolayers (ML). To our knowledge, this is the first direct observation of the diffusion of metal-oxide molecules. The existence of mobile molecules suggests that, at least in some cases, oxide layer formation may be driven by the same processes governing metal-on-metal growth. If the motion is not tip-induced, then an upper limit for the molecule diffusion energy is 0.7 eV, based on the motion of the molecules between successive STM images. Atomic resolution is lost above 0.06 ML, probably because the Au reconstruction is lifted allowing a large increase in the rate of adatom diffusion.