TEMPERATURE-DEPENDENCE OF ULTRAVIOLET-ABSORPTION CROSS-SECTIONS OF ALTERNATIVE CHLOROFLUOROETHANES

The absorption cross-sections of HCFC-123 (CF3-CHCl2), HCFC-14lb (CH3-CFCl2) and HCFC-142b (CH3-CF2Cl) are measured between 170 and 250 nm for temperatures ranging from 295 to 210 K with uncertainties between 2 and 4%. They are compared with other available determinations. Temperature effects are discussed and parametrical formulae are proposed to compute the absorption cross-section for wavelengths and temperatures useful in atmospheric modelling calculations. Photodissociation coefficients are presented and their temperature-dependence is discussed.