RARE-GAS SCATTERING FROM MOLTEN METALS EXAMINED WITH CLASSICAL SCATTERING-THEORY

Classical limit expressions of the differential reflection coefficient for atoms scattering from a surface are compared with recent experime nts for the scattering of monoenergetic beams of Ne, Ar, and Xe with i ncident energies in the eV range from the molten metal surfaces Ga, In , and Bi. We find that single collision events usually make the greate st contribution to the backscattered intensity, double collision event s make a significant but smaller contribution, and scattering of atoms that are completely trapped and subsequently thermally desorbed has a small probability. In the case of large mass incident projectiles and small mass target atoms we find some evidence for collective mass eff ects of the target. An analysis of the temperature dependence of the i ntensities shows that these surfaces act neither as a smooth continuou s repulsive barrier nor as a collection of discrete scattering centers ; rather they exhibit a behavior in between these two extremes. (C) 19 97 American Institute of Physics.