TY - JOUR
T1 - Kinetic, thermochemical, and spectroscopic study of Cl2O3
AU - Burkholder, James B.
AU - Mauldin, R. L.
AU - Yokelson, R. J.
AU - Solomon, S.
AU - Ravishankara, A. R.
PY - 1993
Y1 - 1993
N2 - The UV absorption spectrum of Cl2O3 between 220 and 320 nm was measured using time-resolved transient absorption. Cl2O3 was produced following 193-nm pulsed laser photolysis of N2O/Cl2/OClO/He or CF2-Cl2/OClO/N2 gas mixtures by reaction 1: ClO + OClO + M → Cl2O3 + M. The absorption spectrum peaks at 267 nm with a cross section of (1.60 -0.22+0.35) × 10-17 cm2 (2σ error limits including estimated systematic errors). The rate coefficient for the forward reaction 1, k1, was measured at temperatures between 200 and 260 K at N2 number densities over the range (1.1-10.9) × 1018 molecules cm-3. The data were fit using the Troe formalism, with an Fc fixed at 0.6, to yield k0(300) = (6.2 ± 1.0) × 10-32 cm6 molecule-2 s-1, k∞ = (2.4 ± 1.2) × 10-11 cm3 molecule-1 S-1, and n = 4.7 ± 0.6 (2σ error limits). The equilibrium constant for reaction I, Keq, was measured at five temperatures over the range 232-258 K. A second law analysis of this data along with data reported by Hayman and Cox [Chem. Phys. Lett. 1989, 155, 1] yielded ΔS° = -21.2 ± 4.5 cal mol-1 K-1 and ΔH° = -11.1 ± 1.2 kcal mol-1 (2σ error limits of the fit). These photochemical and kinetic results are compared with previously reported values. The kinetic, equilibrium, and photochemical data were included in a photochemical box model of the polar stratosphere to assess the role of Cl2O3 in stratospheric chemistry. On the basis of the results of the model, it is concluded that Cl2O3 does not play a significant role in the polar stratosphere.
AB - The UV absorption spectrum of Cl2O3 between 220 and 320 nm was measured using time-resolved transient absorption. Cl2O3 was produced following 193-nm pulsed laser photolysis of N2O/Cl2/OClO/He or CF2-Cl2/OClO/N2 gas mixtures by reaction 1: ClO + OClO + M → Cl2O3 + M. The absorption spectrum peaks at 267 nm with a cross section of (1.60 -0.22+0.35) × 10-17 cm2 (2σ error limits including estimated systematic errors). The rate coefficient for the forward reaction 1, k1, was measured at temperatures between 200 and 260 K at N2 number densities over the range (1.1-10.9) × 1018 molecules cm-3. The data were fit using the Troe formalism, with an Fc fixed at 0.6, to yield k0(300) = (6.2 ± 1.0) × 10-32 cm6 molecule-2 s-1, k∞ = (2.4 ± 1.2) × 10-11 cm3 molecule-1 S-1, and n = 4.7 ± 0.6 (2σ error limits). The equilibrium constant for reaction I, Keq, was measured at five temperatures over the range 232-258 K. A second law analysis of this data along with data reported by Hayman and Cox [Chem. Phys. Lett. 1989, 155, 1] yielded ΔS° = -21.2 ± 4.5 cal mol-1 K-1 and ΔH° = -11.1 ± 1.2 kcal mol-1 (2σ error limits of the fit). These photochemical and kinetic results are compared with previously reported values. The kinetic, equilibrium, and photochemical data were included in a photochemical box model of the polar stratosphere to assess the role of Cl2O3 in stratospheric chemistry. On the basis of the results of the model, it is concluded that Cl2O3 does not play a significant role in the polar stratosphere.
UR - http://www.scopus.com/inward/record.url?scp=0000693802&partnerID=8YFLogxK
U2 - 10.1021/j100131a032
DO - 10.1021/j100131a032
M3 - Article
AN - SCOPUS:0000693802
SN - 0022-3654
VL - 97
SP - 7597
EP - 7605
JO - Journal of Physical Chemistry
JF - Journal of Physical Chemistry
IS - 29
ER -