Depletion Kinetics of Nickel Atoms by Sulfur Dioxide

Abstract

The gas-phase depletion kinetics of Ni(a3FJ, a3DJ) in the presence of SO2 are reported. Nickel atoms were produced by the 248 nm photodissociation of nickelocene and detected by laser-induced fluorescence. The ground term of Ni, a3F4, and the two lowest energy spin−orbit states, a3D3 and a3D2, were found to react termolecularly (and with identical rate constants) with SO2, an indication of rapid interconversion between these states. The limiting low-pressure third-order rate constant, measured over the temperature range 296−612 K, can be expressed as ko(T) = 7.455−24.41(log T) + 3.993(log T)2 cm6 molecule-2 s-1. A binding energy of 47 kcal mol-1 was estimated by combining the kinetic results with unimolecular rate theory and density functional methods. The limiting high-pressure second-order rate constant over the temperature range is on the order of the collision rate. The other spin−orbit states of both terms depleted quite rapidly in the presence of SO2, with rate constants also on the order of the col...