Low-energy-electron transmission in solid krypton and xenon films.

Abstract

Low-energy-electron-transmission (LEET) spectra of krypton and xenon films deposited on a platinum substrate exhibit a peak at an energy somewhat below the center of the respective ${\mathrm{\ensuremath{\Gamma}}}_{3/2}$n=1 exciton band. The peaks were systematically studied as a function of the film thickness. They were attributed to a process in which an electron loses a large part of its energy by creating a ${\mathrm{\ensuremath{\Gamma}}}_{3/2}$n=1 exciton and consequently ends up in the conduction band of the rare-gas solid beneath the vacuum level. A simple model was formulated, taking into account the shape of the optical-absorption band and the image forces at the sample boundaries. Fitting the position, width, and height of the experimentally observed peaks in the thickest films (\ensuremath{\sim}100 monolayers or more) lead to the determination of the conduction-band energy ${\mathit{V}}_{0}$ and exciton band parameters in good agreement with the results of photoelectric and optical-absorption experiments. However, for thinner films the LEET peaks were much broader than predicted by theory. The possible reasons for this behavior are discussed in brief.