## Abstract

Rate coefficients for the pyrolysis of SO_{2} in Ar in the temperature range 2188-4249 K were determined using a diaphragmless shock tube. The concentration of O atoms was monitored with resonance absorption. Rate coefficients determined in this work show Arrhenius behavior, with k _{la}(T) = (4.86 ± 1.31) × 10^{-9} exp [-(50450 ± 730)/T] cm^{3} molecule^{-1} s^{-1}; listed errors represent one standard deviation in fitting. These values are consistent with some previous measurements that show a preexponential factor and activation energy greater than other measurements. Theoretical calculations at the G2M(RCC2) level, using geometries optimized with the B3LYP/6-311+G(3df) method, yield energies of transition states and products relative to those of the reactants. Rate coefficients predicted with a microcannonical variational RRKM theory agree well with experimental observations; contributions from electronically excited states of SO_{2} are significant. Rate coefficients for the recombination O + SO → SO_{2} are predicted to decrease with temperature with k_{10a}(T) = (4.82 ± 0.05) × 10^{-31}(T/298)-^{2.17±0.03} cm^{6} molecule^{-2} s^{-1} for the temperature range 298-3000 K. In some experiments, S atoms were monitored with resonance absorption. With detailed chemical modeling, we found that S atoms were mainly produced from the secondary reaction O + SO → S + O_{2} rather than from direct pyrolysis of SO_{2} or from further pyrolysis of the SO product. Rate coefficients for this secondary reaction, determined to be k_{10b}(T) = (3.0 ± 0.3) × 10^{-11} exp [-(6980 ± 280)/T] cm ^{3} molecule^{-1} s^{-1}, agree closely with the theoretically predicted value comprising three product-channels via one triplet and two singlet SOO intermediates.

Original language | English |
---|---|

Pages (from-to) | 11020-11029 |

Number of pages | 10 |

Journal | Journal of Physical Chemistry A |

Volume | 107 |

Issue number | 50 |

DOIs | |

State | Published - 18 Dec 2003 |

## Fingerprint

Dive into the research topics of 'Experiments and Calculations on Rate Coefficients for Pyrolysis of SO_{2}and the Reaction O + SO at High Temperatures'. Together they form a unique fingerprint.