A Universal Formula for the Secondary Electron Yield of Metals at an Incident Angle of θ

Abstract

Based on the main physical processes, we deduce the relationships among the incident energy Wp0 of the primary electron, the number of released secondary electrons (i.e. δPEθ) per primary electron entering the metal at incident angle θ and the angle θ itself. In addition, the relationship of δPEθ at θ = 0°, i.e. δPE0, with Wp0 is determined. From the experimental results, the relationship of the ratio at θ = 0°, i.e. β0 which is the ratio of the average number of released secondary electrons generated by a single primary electron backscattered at the metal surface to that generated by a single primary electron entering the metal, with Wp0 is determined. Moreover, the relationships among the ratio βθ, Wp0 and θ are obtained. Based on the relationships among the secondary electron yield at θ (i.e. δθ), the yield at θ = 0° (i.e. δ0), the backscattering coefficient at 0 (i.e. ηθ), the coefficient at θ = 0° (i.e. η0), δPEθ and δPE0 we deduce the universal formula for δθ, δ0, ηθ, η0, and Wp0 for the primary electrons at an incident energy of 2–10 keV. The secondary electron yields calculated from the universal formula and the experimental yields of some metals are compared, and the results suggest that the proposed formula is universal for estimation of secondary electron yields at θ = 0°–80°.