Gas-phase kinetics of ground-state platinum with O2,NO, N2Oand CH4

Abstract

The gas-phase reactivity of ground-state platinum with O₂, NO, N₂O and CH₄ is reported. Platinum atoms were produced by the photodissociation of [Pt(CH₃)₃(C₅H₄CH₃)] and detected by laser-induced fluorescence. The reaction rates of platinum with all the reactants are pressure dependent indicating adduct formation; however, the reaction with N₂O has a bimolecular component. The room-temperature limiting low-pressure third-order rate constants in argon buffer are (2.3±0.2)×10^-31 molecule^-2 cm⁶ s^-1, (4.3±0.4)×10^-31 molecule^-2 cm⁶ s^-1, (3.7±0.5)×10^-31 molecule^-2 cm⁶ s^-1 and (2.1±0.9)×10^-28 molecule^-2 cm⁶ s^-1 for O₂, NO, N₂O and CH₄, respectively, where the uncertainties are ±2σ. The limiting high-pressure second-order rate constants are (2.5±0.5)×10^-12 molecule^-1 cm³ s^-1, (2.3±0.8)×10^-11 molecule^-1 cm³ s^-1, (2.3±0.3)×10^-12 molecule^-1 cm³ s^-1 and (6.3±0.3)×10^-12 molecule^-1 cm³ s^-1 for O₂, NO, N₂O and CH₄, respectively. The second-order rate constant for the abstraction channel for the reaction with N₂O at 296 K is approximately 1×10^-13 molecule^-1 cm³ s^-1.