Effects of O₂ Adsorption on the Secondary Electron Emission Properties

Abstract The surface adsorption of gas molecules is a key factor limiting the secondary electron yield (SEY) of a material in many areas of applied physics. This paper investigates the impact of O2 adsorption on the SEY of metallic Ag. To account for the particle distribution, we describe a B.E.T. based multilayer O2 physisorption model. Furthermore, based on the phenomenological model of secondary electron emission and taking into account the different scattering processes between electrons and particles in the adsorbed layer, we obtained a numerical model of SEY in the adsorbed state using Monte Carlo simulations. The relationship among O2 adsorption, adsorption layer thickness, and SEY variation characteristics were then examined through a series of experiments. After 12 hours of O2 exposure, it was discovered that the clean samples exhibited a 12 to 19 percent increase in the maximum value of SEY and a 2.3 nm increase in the thickness of the adsorbed layer. Experiment results were also compared to the MC model to determine if the model was accurate.