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Rate constant for the reaction of OH with CH 3 CCl 2 F (HCFC‐141b) determined by relative rate measurements with CH 4 and CH 3 CCl 3
Author(s) -
Huder Karin,
DeMore William B.
Publication year - 1993
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 - 10.1029/93gl01766
Subject(s) - ozone , reaction rate constant , analytical chemistry (journal) , arrhenius equation , atmospheric temperature range , chemistry , atmosphere (unit) , water vapor , materials science , thermodynamics , kinetics , activation energy , physics , environmental chemistry , organic chemistry , quantum mechanics
Determination of accurate rate constants for OH abstraction is of great importance for the calculation of lifetimes for HCFCs and their impact on the atmosphere. For HCFC‐141b there has been some disagreement in the literature for absolute measurements of this rate constant. In the present work rate constant ratios for HCFC‐141b were measured at atmospheric pressure in the temperature range of 298–358K, with CH 4 and CH 3 CCl 3 as reference gases. Ozone was photolyzed at 254 nm in the presence of water vapor to produce OH radicals. Relative depletions of 141b and the reference gases were measured by FTIR. Arrhenius expressions for 141b were derived from each reference gas and found to be in good agreement with each other. The combined expression for HCFC‐141b which we recommend is 1.4×10 −12 exp(−1630/T) with k at 298 K being 5.9×10 −15 cm³/molec‐s. This value is in excellent agreement with the JPL 92–20 recommendation.