Field-induced dissociation of O2* in a fast beam

A keV energy beam of O2 produced by charge transfer of O2+ (a4Πu) in Cs vapor is found to be rapidly (τ≤ 35 ns) predissociated during passage through a 300 μm wide slit. Spatial and temporal analysis of the correlated dissociation fragments locate the dissociating O2* levels at an energy ∼ 0.02 eV below the vibrational levels of O2+ X2Πg and reveal predissociation of at least 7 discrete vibrational levels to the O(1S)+O(1D), O(1D)+O(1D), O(1D)+O(3P), and O(3P)+O(3P) separated atom limits. Studies of the fragmentation as a function of electric field strength applied across the slit suggest that the observed dissociation arises form a mixing of high nl (n>30) Rydberg states built on an X2Πg core that is induced by very weak fields. Predissociation of v > 0 is suppressed by field ionization of these vibrational levels at a rate increasing with applied field. The observed branching among the dissociation channels appears to be relevant to that which would be produced in the dissociative recombination of O2+(X2Πg,v)