An angle-resolved dissociative photoionization study of the c4Σu- state in O2+ using the TPEPICO technique

We have investigated the angular distributions of O+(S-4) ions produced from dissociative photoionization of O(2)(+)c(4)Sigma(-)(u) (nu = 0, 1) using the TPEPICO technique, i.e. by measuring the coincidence yield between threshold photoelectrons and photoions. The vibrational levels have distinctly different lifetimes, tau(nu), which diminish their inherent anisotropic photoion angular distribution characterized by a beta parameter. We obtain tau(1) = 6.0 +/- 0.3 x 10(-14) s and a lower limit on tau(0) of approximate to 1 x 10(-12) s, in broad agreement with other experimental studies using different methods, and find that beta = 0.40 +/- 0.05, which is significantly at variance with the predicted value of >= 1.6.