Physical Adsorption and Surface Potential Measurements on Evaporated Metal Films Bearing Sodium Deposits

Abstract

AbstractThe interaction of sodium with steel surfaces is of interest in reactor technology. We have therefore developed methods of measuring sub‐monolayer concentrations of sodium deposited on evaporated metal films and used these methods to examine the stability of sodium overlays. Surface sodium is estimated by: Continuous recording of the surface potential due to sodium using the diode method Observing the fall in surface potential due to physically adsorbed xenon Observing the fall in monolayer value for physically adsorbed xenon which occurs at the same time, and Extracting heat data from the adsorption isotherms. Sodium overlays on copper and on iron show no tendency to mix over the temperature range studied (77 K to 423 K) but sodium appears to overrun the internal structure of films at an appreciable rate above 273 K.