Kinetic emission of electrons from monocrystalline targets

This paper develops a single-collision theory of the emission of electrons from a metal surface subjected to high-energy ion bombardment, which gives reasonable agreement with the data of Carlston, Magnuson, Mahadevan, and Harrison, in the 1to 10-keV energy range. The model is based upon a Thomas-Fermi-Firsov energy-transfer calculation which has been modified to include an explicit dependence upon lattice orienta­tion. Orientation effects appear naturally, and orientation-dependent cross sections are not required, but the distribution of possible impact parameters for a particular crystal orientation is of central importance. The theory has been used to determine semiempirical interaction potentials between the moving particle and a lattice atom. These potentials are more similar to Abrahamson's atom-atom potentials than to the Gibson potentials used in radiation-damage studies.Work supported by the U.S. Office of Naval ResearchApproved for public release; distribution is unlimited

Electron ejection from single crystals due to 1- to 10-keV noble-gas ion bombardment

The secondary-electron ejection coeKcient y has been measured for the (110), (100), and (111)planes of Cu, Al, Ag, Ni, and Mo bombarded by the singly charged noble-gas ions Ne+, Ar+, Kr+, and Xe+ in the energy range from 1 to 10 keV. Surfaces were kept clean to within a fraction of a monolayer contamination by the sputtering action of the incident ion beams. The ratios ys&t/ys'q, 't' are quite constant, which would tend to indicate a theoretical model based on simple geometrical considerations of the opacity of the single crystal planes. However, the fact that the ratios are relatively insensitive to the ion-bombardment energy indicates that a model based upon the transparency of the target is not sufficient to explain the phenomenon. The dependence of y on the bombarding-ion mass is also explored