The Dissociative Ionization in Oxygen.

Dissociative ionization in O2 has been examined by means of a retarding potential lens combined with a quadrupole mass spectrometer. This particular arrangement made possible detailled analysis of the O+ ions kinetic energy distribution and the measurement of threshold energies of O+ ions with known kinetic energy. These two types of informations bring new experimental evidence, besides direct dissociative ionization of O2, for predissociation of the B2Sigma-/g state, the 2Piu state and the c4Sigma-/u state of O2+. A new predissociation of the O2+(2Deltag) state has been found. At low ion energy the predissociation of the 2Phiu state or an autoionizing predissociation is observed.