Mass-Spectrometric Studies of Corona Discharges in Air at Atmospheric Pressures

Abstract

Mass-spectrometric studies of the ionic species formed in corona discharges in nitrogen, oxygen, and air have been carried out at water concentrations from 1.7×10−2 to 0.65 mole % and total pressures up to one atmosphere. The importance of water in this system has been demonstrated by the dominant presence of (H2O)nH+ ion clusters at water concentrations as low as 4.1×10−2 mole %. Evidence is presented for the formation (HO2)+ and (N2H)+ ions as possible intermediates in the formation of these clusters. It is argued that hydride formation by the primary ions and possibly charge-exchange reaction with water molecules followed by proton-transfer reactions are the mechanisms by which these clusters are produced. Simple hydration of other ionic species of the discharge, e.g., O2+(H2O)n, NO+(H2O)n, and (NO2+) (H2O)n, at water concentrations below 5.5×10−2 mole % have also been observed.