Scattering of Atomic Beams by Polycrystalline Nickel

Abstract

The results of recent experimental studies of the scattering of beams of Kr, Ar, Ne, He, and D₂ from carbonized polycrystalline nickel targets are presented and compared with the findings of other investigations of the phenomenology of heavy particle scattering at a solid surface. In the present experiments, as in certain earlier experiments utilizing alkali—halide cleavage planes, large deviations from diffuse (cosine law) scattering are observed, which have not yet been satisfactorily interpreted. The present series of experiments tends to support a model for the scattering mechanism in which a fraction of the incident molecules are scattered diffusely and the remainder are scattered preferentially. From experimental observations, it is inferred that the slower particles in the incident beam contribute to the diffuse component while the faster particles are scattered preferentially. In addition, an angular variation in the degree of thermal accommodation of the incident particles is observed.