On the Measurement of the Backscattering Coefficient for Low Energy Electrons

Abstract

An electron detector for the measurement of backscattering and secondary electron coefficients based on that of Reimer and Tollkamp has been devised and built. The detector is used in ultra high vacuum and allows one to use in-situ ion bombardment of the sample to remove surface contaminants before data collection. New experimental measurements of the backscattering and secondary electron coefficients in the energy range 0.5-6keV are reported for C, Al, Si, Cu, Ge, Mo, Ag and Au. These are collected from both argon ion cleaned and as-inserted surfaces. The back- scattering coefficients of the argon ion cleaned surfaces monotonically increases for elements of atomic number Z (graterthan) 28 whilst it decreases for elements of Z (lessthan) 28 for all energies used. This is in contrast to the as-inserted surfaces that show a more complex pattern below 1 keV incident energies.