Temperature dependence of ultraviolet absorption cross-sections of chlorofluoroethanes
ultraviolet absorption cross-section
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New absorption cross-sections of three haloethanes C 2F 5Cl, C 2F 4Cl 2 (CF 2Cl-CF 2Cl), and C 2F 3Cl 3 (CF 2 Cl-CFCl 2) measured between 172 and 250 nm for temperatures ranging from 225 to 295 K, are presented with uncertainties between 2 and 4%. They are compared with previous measurements available at room temperature and only at one low temperature, namely 208 K. The largest temperature effects which take place near the absorption threshold, can amount up to 50% for C 2F 3Cl 3 and 70% for C 2F 4Cl 2; temperature effect, if any, was too small to be detected in the case of C 2F 5Cl. Extrapolated values for temperatures of aeronomical interest are presented as well as parametrical formulae which give absorption cross-section values for given wavelength and temperature useful in stratospheric modelling calculations. Photodissociation coefficients are presented and their temperature dependence is discussed.
CitationSimon, P.C.; Gillotay, D.; Vanlaethem-Meuree, N.; Wisemberg, J. (1988). Temperature dependence of ultraviolet absorption cross-sections of chlorofluoroethanes. , Annales Geophysicae, Vol. 6, Issue 3, 239-248,