KINETICS OF THE SN(P-3(0)) REACTIONS WITH CO2 AND O-2 OVER WIDE TEMPERATURE RANGES

Rate coefficients for the title reactions have been measured by the hi gh-temperature fast-flow reactor (HTFFR) technique. The relative conce ntrations of Sn ground-state atoms were monitored by laser-induced flu orescence (LIF) for Sn + CO2 --> SnO + CO and by either LIF or atomic resonance absorption for the Sn + O-2 --> SnO + O reaction. Results fr om these two diagnostic methods agree very well. We obtained, in units of cm(3) molecule(-1) s(-1), k(1)(690-1600 K) = 2.3 x 10(-10) exp(-91 00 K/T) and k(2)(380-1840 K) = (5.1 x 10(-13))(T/K)(0.79) exp(-437 K/T ), with 2 sigma accuracy limits of about +/-25%. The results are compa red to other metal atom reactions with these oxidants. All have simila rly large preexponentials. The magnitudes of the exponential terms are shown to be typical for a spin-forbidden and a spin-allowed reaction, respectively.