GAS-PHASE KINETICS OF GROUND-STATE PLATINUM WITH O-2, NO, N2O AND CH4

The gas-phase reactivity of ground-state platinum with O-2, NO, N2O an d CH4 is reported. Platinum atoms were produced by the photodissociati on of [Pt(CH3)(3)(C5H4CH3)] and detected by laser-induced fluorescence . The reaction rates of platinum with all the reactants are pressure d ependent indicating adduct formation; however, the reaction with N2O h as a bimolecular component. The room-temperature limiting low-pressure third-order rate constants in argon buffer are (2.3 +/- 0.2) x 10(-31 ) molecule(-2) cm(6) s(-1), (4.3 +/- 0.4) x 10(-31) molecule(-2) cm(6) s(-1), (3.7 +/- 0.5) x 10(-31) molecule(-2) cm(6) s(-1) and (2.1 +/- 0.9) x 10(-28) molecule(-2) cm(6) s(-1) for O-2, NO, N2O and CH4, resp ectively, where the uncertainties are +/-2 sigma. The limiting high-pr essure second-order rate constants are (2.5 +/- 0.5) x 10(-12) molecul e(-1) cm(3) s(-1), (2.3 +/- 0.8) x 10(-11) molecule(-1) cm(3) s(-1), ( 2.3 +/- 0.3) x 10(-12) molecule(-1) cm(3) s(-1) and (6.3 +/- 0.3) x 10 (-12) molecule(-1) cm(3) s(-1) for O-2, NO, N2O and CH4, respectively. The second-order rate constant for the abstraction channel for the re action with N2O at 296 K is approximately 1 x 10(-13) molecule(-1) cm( 3) s(-1).