Negative Ion/Molecule Reactions in a Negative Corona Discharge

摘要

An atmospheric pressure negative corona discharge (point to plane) coupled to a quadrupole mass spectrometer was used to study negative ion/molecular chemistry. It was shown that neutral intermediates, mainly 03, N02 and N0, are produced by high energy electron dissociation of air constituents in a very narrow volume close to the point electrode. The neutrals are transported by air flow or diffuse into the discharge gap and undergo ion/molecule reaction initiated by the 02-and 0-ion. A tentative ion/molecular reaction scheme was proposed. Furthermore a reduction of the negative ions N02, N03, C03 and 03 to less than 1% was possible in zero air by flowing a nonelectronegative gas around the point electrodes. In room air the negative ions N03, 03 and C03 were reduced by approximately 95%. The N02 ion increases indicating it is present in room air.