AVS 50th International Symposium
    Surface Science Monday Sessions
       Session SS3-MoM

Paper SS3-MoM11
STM Tip-induced Translation through Excitations of the H@sub 2@O and D@sub 2@O Bending Modes on Pd(111)

Monday, November 3, 2003, 11:40 am, Room 328

Session: Surface Diffusion and Wetting
Presenter: E. Fomin, University of California at Berkeley
Authors: E. Fomin, University of California at Berkeley
T. Mitsui, Lawrence Berkeley National Laboratory
M.K. Rose, University of California at Berkeley
D.F. Ogletree, Lawrence Berkeley National Laboratory
M. Salmeron, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
We have studied the adsorption and manipulation of H@sub 2@O and D@sub 2@O molecules on Pd(111) using low temperature (~40 K) scanning tunneling microscopy (STM). We investigated the temperature dependence of molecular diffusion using two different approaches: tracking of individual molecules with the STM tip sitting on top of the molecules; and a "movie" technique - a series of consecutive scans showing hopping for an ensemble of molecules. In the course of this work it became clear that under certain conditions the STM tip had a strong influence on molecular motion. We found that the tip-induced hopping rate starts to grow exponentially as the bias reaches 200 meV for H@sub 2@O or 160 meV for D@sub 2@O, which corresponds to the molecular bending-mode excitation energy. This allows us to propose a coupling between vibrational excitation and molecular translation for water on Pd(111).