AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA5
Charge Transfer in Low Energy Li Ion Scattering from Halogen-covered Metal Surfaces

Wednesday, November 6, 2002, 3:20 pm, Room C-108

Session: Gas-Surface Dynamics
Presenter: Y. Yang, University of California, Riverside
Authors: Y. Yang, University of California, Riverside
J.A. Yarmoff, University of California, Riverside
Correspondent: Click to Email
Resonant charge transfer (RCT) for 400-3000 eV Li ions scattered from iodine- and bromine-covered Fe(110) and Ni(100) surfaces is probed with time-of-flight spectroscopy. RCT with alkali ions has traditionally been considered to reflect the overlap between the local surface potential and the ionization level of the exiting ion. In this work, it is shown that the local charge density can also influence the RCT process. For example, iodine would be expected to adsorb with some net negative charge, thereby producing a dipole directed into the surface that would raise the work function. In contrast, iodine decreases the work function, and the neutralization probabilities for Li singly scattered from the I sites are always higher than for scattering from metal sites. Thus, there is a local effect involved in RCT for this system. Bromine adsorption does not change the work function significantly, but still the neutralization probabilities for scattering from Br sites are larger than from the substrate. These results suggest that the local charge density does plays a significant role in determining the RCT probability.