Insulator–insulator contact charging and its relationship to atmospheric pressure ☆

Metal–metal and metal–insulator contact charging are well-known phenomena with good theoretical understanding. However, insulator–insulator charging is not as well understood. Surface ion exchange is suspected of being the mechanism of insulator–insulator triboelectric charging. Experiments have shown that the amount of charge exchange is highly dependent on the atmospheric pressure of the gas. We present a two-phase model based on an ideal gas of singly-charged ions in equilibrium with a submonolayer adsorbed film.