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The reaction Cl + H 2 CO→ HCl + HCO: Decreased sensitivity of stratospheric ozone to chlorine perturbations
Author(s) -
Stief L. J.,
Michael J. V.,
Payne W. A.,
Nava D. F.,
Butler D. M.,
Stolarski R. S.
Publication year - 1978
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl005i010p00829
Subject(s) - ozone , chlorine , stratosphere , formaldehyde , ozone depletion , chemistry , reaction rate constant , analytical chemistry (journal) , ozone layer , flash photolysis , resonance fluorescence , photodissociation , ammonia , methane , reaction rate , photochemistry , atmospheric sciences , environmental chemistry , fluorescence , catalysis , kinetics , physics , organic chemistry , biochemistry , quantum mechanics
The absolute rate constant for the reaction Cl + H 2 CO → HCl + HCO has been determined by the flash‐photolysis‐resonance fluorescence method to be 7.5 ± 0.9 (2σ) × 10 −11 cm³ molecule −1 sec −1 at 298K and to have a negligible temperature dependence. This rate which at stratospheric temperatures is more than 2000 times faster than the rate of Cl + CH 4 and more than a factor of 2 faster than Cl + HO 2 , indicates that formaldehyde (H 2 CO) will compete significantly with methane (CH 4 ) and HO 2 for the conversion of active chlorine in the stratosphere to the inactive reservoir HCl. Chlorine will thus be a less efficient destroyer of stratospheric ozone than previously believed. One‐dimensional eddy‐diffusion photochemical model calculations indicate that the eventual ozone depletion for a steady‐state CFM release at 1975 rates (750,000 tons/year) will be lowered from 20% to 18.5% by the inclusion of this reaction.