Electron and Negative Ion Mobilities in Oxygen, Air, Nitrous Oxide and Ammonia

Abstract

The electrical shutter method for measuring electron mobilities in gases has been extended to include experiments in oxygen, air, nitrous oxide and ammonia. The experimental data support the hypothesis that collisions of low energy electrons with molecules of these gases may be inelastic. Such collisions cause excitation of vibrational levels, electronic levels, or dissociation of the molecule. The results are compared with experiments reported elsewhere on negative ion formation in these gases. In general the onset of negative ion formation is accompanied by inelastic collisions which result in a marked increase in the electron drift velocity. Negative ion mobilities in these gases have been measured in the same apparatus by an adaptation of the Rutherford alternating current method. The ions were formed by electron attachment in an auxiliary field and their mobility determined at various ages. The probable character of the ions is discussed after comparing the experimental results with those predicted by the Langevin theory.