AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeA

Invited Paper SS2-WeA5
Atom Scattering From Atomic Surfactants

Wednesday, October 27, 1999, 3:20 pm, Room 607

Session: Gas-Surface Dynamics
Presenter: G.M. Nathanson, University of Wisconsin, Madison
Authors: G.M. Nathanson, University of Wisconsin, Madison
J.A. Morgan, University of Wisconsin, Madison
W.R. Ronk, University of Wisconsin, Madison
M. Manning, University of Wisconsin, Madison
Correspondent: Click to Email
Scattering experiments show that the rate of energy transfer between atomic gases and atomic liquids can be controlled by altering only the composition of the outermost surface layer of atoms. In the case of the 0.2% bismuth/99.8% gallium liquid alloy, the surface composition can be varied from a nearly pure Bi monolayer at temperatures near 290 K to 80% surface Ga at 900 K. This Bi surface enrichment is due to the much lower surface tension of pure Bi than of pure Ga. We find that impinging argon and xenon atoms lose nearly the same amount of energy in collisions with pure liquid Bi as with the bismuth-covered Bi/Ga alloy created at low temperatures. With increasing temperature, the rate of collisional energy transfer increases nearly linearly toward the value for pure liquid Ga as the surface Bi atoms are replaced by Ga atoms. These results suggest that the Ga atoms underneath the surface Bi atoms do not play a direct role in controlling the exit energies of the inelastically scattered Ar or Xe atoms; the rate of approach to gas-liquid thermal equilibrium depends only on the composition of the outermost surface layer.