Atmospheric Lifetime of CHF2Br, a Proposed Substitute for Halons

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Science  03 May 1991:
Vol. 252, Issue 5006, pp. 693-695
DOI: 10.1126/science.252.5006.693


The rate coefficients, k1, for the reaction of OH with CHF2Br have been measured using pulsed photolysis and discharge flow techniques at temperatures (T) between 233 and 432 K to be k1, = (7.4 ± 1.6) x 10–13 exp[-(1300 ± 100)/T] cubic centimeters per molecule per second. The ultraviolet absorption cross sections, σ, of this molecule between 190 and 280 nanometers were measured at 296 K. The k1, and σ values were used in a one-dimensional model to obtain an atmospheric lifetime of approximately 7 years for CHF2Br. This lifetime is shorter by approximately factors of 10 and 2 than those for CF3Br and CF2ClBr, respectively. The ozone depletion potentials of the three compounds will reflect these lifetimes.

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