Angular dependence of the secondary electron emission crystal current : effects of surface modification

Abstract

The variation of the angle between the incident electron beam and sample surface contributes in two ways to the secondary electron emission from single crystals. These contributions are a monotonically varying background due to the changing number ofsecondaries produced near the surface, and an oscillatory component previously explained as a bulk effect related to Kikuchi patterns. This work shows that for emission from a Au(111) surface, the background can be described well by a simple model based on the semiempirical theory of Kanaya and Kawakatsu. It also provides additional support for the explanation of the oscillations as a bulk effect by showing that the oscillation amplitude remains essentially unchanged either by surface sputtering or by the deposition of a thin lead layer. The presence of these oscillations requires some care ill the use of the secondary electron crystal current as a measure of the thickness of thin metal films.