R.Li, K.A. Hanold, M.C. Garner, A.K. Luong and R.E. Continetti, "Excited State Dynamics in Clusters of Oxygen.", Discussions of the Faraday Society, No. 108, 115-130 (1998).
Considerable insights into the dynamics of both ionic (photodissociation) and neutral (dissociative photodetachment) decomposition pathways of O4- and O6- have been gained using photoelectron and photofragment translational spectroscopy in a fast-ion-beam. The O4- data at 532 nm reveal a novel process involving sequential photodetachment of an electron with a near-zero binding energy from photodissociating O4-. Studies of O6- at 532 nm reveal that addition of a third O2 to the O4- core leads to a dramatic change in the photodissociation dynamics, producing highly vibrationally excited O2- photofragments not observed in the case of O4-. At 355 nm, both O4- and O6- yield vibrationally excited O2- photofragments, as observed by autodetachment of the nascent O4-(v>=5) --> O2 + e-. At 266 nm, photofragment TOF measurements on O6- and O4- show that the dynamics of dissociative photodetachment in O6- are only slightly perturbed relative to O4-. The anisotropic product angular distribution previously observed in O4- is observed to persist in the three-body neutral decomposition O6- + hv --> O2 + O2 + O2 + e-. The origins of these diverse phenomena in O4- and O6- are discussed.