TY - JOUR
T1 - Disproportionation Channel of the Self-reaction of Hydroxyl Radical, OH + OH → H2O + O, Revisited
AU - Zhang, Xiaokai
AU - Sangwan, Manuvesh
AU - Yan, Chao
AU - Koshlyakov, Pavel V.
AU - Chesnokov, Evgeni N.
AU - Bedjanian, Yuri
AU - Krasnoperov, Lev N.
N1 - Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/5/21
Y1 - 2020/5/21
N2 - The rate constant of the disproportionation channel 1a of the self-reaction of hydroxyl radicals OH + OH → H2O + O (1a) was measured at ambient temperature as well as over an extended temperature range to resolve the discrepancy between the IUPAC recommended value (k1a = 1.48 × 10-12 cm3 molecule-1 s-1, discharge flow system, Bedjanian et al. J. Phys. Chem. A 1999, 103, 7017) and a factor of ca. 1.8 higher value by pulsed laser photolysis (2.7 × 10-12 cm3 molecule-1 s-1, Bahng et al. J. Phys. Chem. A 2007, 111, 3850, and 2.52 × 10-12 cm3 molecule-1 s-1, Altinay et al. J. Phys. Chem. A 2014, 118, 38). To resolve this discrepancy, the rate constant of the title reaction was remeasured in three laboratories using two different experimental techniques, namely, laser-pulsed photolysis-transient UV absorption and fast discharge flow system coupled with mass spectrometry. Two different precursors were used to generate OH radicals in the laser-pulsed photolysis experiments. The experiments confirmed the low value of the rate constant at ambient temperature (k1a = (1.4 ± 0.2) × 10-12 cm3 molecule-1 s-1 at 295 K) as well as the V-shaped temperature dependence, negative at low temperatures and positive at high temperatures, with a turning point at 427 K: K1a = 8.38 × 10-14 × (T/300)1.99 × exp(855/T) cm3 molecule-1 s-1 (220-950 K). Recommended expression over the 220-2384 K temperature range: K1a = 2.68 × 10-14 × (T/300)2.75 × exp(1165/T) cm3 molecule-1 s-1 (220-2384 K).
AB - The rate constant of the disproportionation channel 1a of the self-reaction of hydroxyl radicals OH + OH → H2O + O (1a) was measured at ambient temperature as well as over an extended temperature range to resolve the discrepancy between the IUPAC recommended value (k1a = 1.48 × 10-12 cm3 molecule-1 s-1, discharge flow system, Bedjanian et al. J. Phys. Chem. A 1999, 103, 7017) and a factor of ca. 1.8 higher value by pulsed laser photolysis (2.7 × 10-12 cm3 molecule-1 s-1, Bahng et al. J. Phys. Chem. A 2007, 111, 3850, and 2.52 × 10-12 cm3 molecule-1 s-1, Altinay et al. J. Phys. Chem. A 2014, 118, 38). To resolve this discrepancy, the rate constant of the title reaction was remeasured in three laboratories using two different experimental techniques, namely, laser-pulsed photolysis-transient UV absorption and fast discharge flow system coupled with mass spectrometry. Two different precursors were used to generate OH radicals in the laser-pulsed photolysis experiments. The experiments confirmed the low value of the rate constant at ambient temperature (k1a = (1.4 ± 0.2) × 10-12 cm3 molecule-1 s-1 at 295 K) as well as the V-shaped temperature dependence, negative at low temperatures and positive at high temperatures, with a turning point at 427 K: K1a = 8.38 × 10-14 × (T/300)1.99 × exp(855/T) cm3 molecule-1 s-1 (220-950 K). Recommended expression over the 220-2384 K temperature range: K1a = 2.68 × 10-14 × (T/300)2.75 × exp(1165/T) cm3 molecule-1 s-1 (220-2384 K).
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U2 - 10.1021/acs.jpca.0c00624
DO - 10.1021/acs.jpca.0c00624
M3 - Article
C2 - 32396004
AN - SCOPUS:85085264836
SN - 1089-5639
VL - 124
SP - 3993
EP - 4005
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 20
ER -