Experimental and theoretical studies of the rate coefficients of the reaction O(P-3)+HCl at high temperatures

Abstract

Rate coefficients of the reaction O(P-3) + HCl in the temperature range 1093-3197 K were determined using a diaphragmless shock tube. O atoms in the ground electronic P-3 states were generated either by photolysis Of SO2 with a KrF excimer laser at 248 nm or by pyrolysis of N2O with the shock wave. Their concentrations were monitored via atomic resonance absorption excited by emission from a microwave-discharged mixture of O-2 and He. Rate coefficients determined in this work show non-Arrhenius behavior, with values consistent with previously reported. measurements for T < 1486 K; they fit well with the equation k(1)(T) = (9.27 +/- 0.03) X 10(-24) T3.67+/-0.18 exp[-(1030 +/- 160)/T] cm(3) molecule(-1) s(-1); listed errors represent one standard deviation in fitting. Theoretical calculations at the CCSD(T)/6-311 +G(d, p) level locate a bent (3)A" (TS1) and a linear (3)A' (TS3) transition state characterized previously. On the basis of the results computed by CCSD(T)/ 6-311 +G(3df,2p)//CCSD(T)/6-311 +G(d,p), the rate coefficients predicted with conventional transition-state theory, including Eckart-tunneling corrections and with variational transition-state theory including zero- and small-curvature tunneling corrections, all agree satisfactorily with experimental observations.