Surface Boundary Effect in Electron-Solid Interactions

摘要

Electrons impinging or escaping from a solid surface undergo surface electronic excitations which are competitive in nature to other electron-solid interaction channels. The detailed information about electron inelastic scattering probability for surface excitations at solid surface is also important in reflection electron energy loss spectroscopy. A self energy formalism based on quantum mechanical treatment of interaction of electrons with a semi-infinite medium, which uses the optical dielectric function is considered to study surface boundary effect for planar surfaces of Cu and Ni for various conditions of electron-solid interactions. The total surface excitation probability of an electron while crossing the surface boundary once is numerically computed by integrating surface term of spatial and angular dependent differential inelastic cross sections over energy loss and distance from the surface. It is found that surface effect is prominent for low energy electrons and large oblique angles with respect to surface normal and confined to the close vicinity of surface boundary.