The Effect of Adsorbed Gases on Contact Electrification

Abstract

The magnitude of the electrification produced on contact of quartz and of sodium chloride on nickel in atmospheres of air, oxygen, and nitrogen has been measured. Reproducible pressure-dependent results were obtained that indicate the contact electrification is a surface phenomenon and depends greatly on the nature of the surfaces involved. At least two layers of adsorbed gas play an important part in the phenomenon of contact electrification. In the pressure range from 760 to 30 mm at least one layer of adsorbed gas is removed. In this pressure range the surface covered with adsorbed gas makes the major contribution to the charge separation. At pressures below 0.1 mm at least a second layer of adsorbed gas is removed. In this pressure range the major contribution to the charge separation is made by the surface from which the second layer of gas has been removed. A fit of the data to Langmuir adsorption isotherms was obtained. Water vapor and perhaps hydrogen act as surface poisons in the phenomenon of contact electrification.