TY - JOUR
T1 - High-temperature reactions of O + COS and S + SO2. Abstraction versus substitution channels
AU - Isshiki, Nobuyasu
AU - Murakami, Yoshinori
AU - Tsuchiya, Kentaro
AU - Tezaki, Atsumu
AU - Matsui, Hiroyuki
PY - 2003/4/10
Y1 - 2003/4/10
N2 - The main concern of this study is to investigate the reaction mechanism of O + COS → products (1). Experiments are conducted by use of an excimer laser photolysis shock tube technique, where mixtures of COS and SO2 diluted in Ar are photolyzed behind reflected shock waves. Time-resolved measurements of O and S atoms are conducted by use of atomic resonance absorption spectroscopy, and the overall rate constant of (1) is determined by the O atom decay at temperatures 1250-1600 K, i.e., k1 = 10-10.18±0.26 exp[-(22.5 ± 7.1) kJ·mol-1/RT] cm3 molecule-1 s-1, which is in good agreement with the former recommendation. It is confirmed in this experiment that the S atom is a direct product of reaction 1. By analysis of time profiles of the S atom, the branching fraction of the S production channel O + COS → S + CO2 (1b), α, is determined against the main channel O + COS → CO + SO (1a), where the S atom consumption reactions, S + SO2 → 2SO (2) and S + COS → S2 + CO (3), are inevitably taken into account. The present experimental result is expressed as α = (0.40 ± 0.10) - (202 ± 137)/T(T= 1120-1540 K). Also, in this kinetic analysis, the rate constant of (2) is simultaneously determined to be k2 = l0-11.01±0.33 exp[-(37.8 ± 8.2) kJ·mol-1/RT]. The reaction mechanism of (1) is examined by comparing the experimental results with those of ab initio potential energy surface/transition state theory calculations.
AB - The main concern of this study is to investigate the reaction mechanism of O + COS → products (1). Experiments are conducted by use of an excimer laser photolysis shock tube technique, where mixtures of COS and SO2 diluted in Ar are photolyzed behind reflected shock waves. Time-resolved measurements of O and S atoms are conducted by use of atomic resonance absorption spectroscopy, and the overall rate constant of (1) is determined by the O atom decay at temperatures 1250-1600 K, i.e., k1 = 10-10.18±0.26 exp[-(22.5 ± 7.1) kJ·mol-1/RT] cm3 molecule-1 s-1, which is in good agreement with the former recommendation. It is confirmed in this experiment that the S atom is a direct product of reaction 1. By analysis of time profiles of the S atom, the branching fraction of the S production channel O + COS → S + CO2 (1b), α, is determined against the main channel O + COS → CO + SO (1a), where the S atom consumption reactions, S + SO2 → 2SO (2) and S + COS → S2 + CO (3), are inevitably taken into account. The present experimental result is expressed as α = (0.40 ± 0.10) - (202 ± 137)/T(T= 1120-1540 K). Also, in this kinetic analysis, the rate constant of (2) is simultaneously determined to be k2 = l0-11.01±0.33 exp[-(37.8 ± 8.2) kJ·mol-1/RT]. The reaction mechanism of (1) is examined by comparing the experimental results with those of ab initio potential energy surface/transition state theory calculations.
UR - http://www.scopus.com/inward/record.url?scp=0344942493&partnerID=8YFLogxK
U2 - 10.1021/jp0200829
DO - 10.1021/jp0200829
M3 - Article
AN - SCOPUS:0344942493
VL - 107
SP - 2464
EP - 2469
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 14
ER -