Effects of O2 adsorption on 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. The influence of O2 adsorption on the SEY of metallic Ag is investigated in this work. To account for the particle distribution, we propose a BET theory based on multilayer O2 physisorption model. Furthermore, based on the phenomenological model of secondary electron (SE) emission and by taking into account the different scattering processes between electrons and particles in the adsorbed layer, we develop a numerical model of SEY in the adsorbed state using Monte Carlo simulations. The relationships among O2 adsorption, adsorption layer thickness, and SEY variation characteristics are then examined through a series of experiments. After 12-h exposure to O2, the clean samples increases 12%–19% of the maximum value of SEY and 2.3 nm in thickness of the adsorbed layer. Experimental results are also compared with the results from the MC model to determine whether the model is accurate.