Ultraviolet absorption spectrum of trifluoro-bromo-methane,difluoro-dibromo-methane and difluoro-bromo-chloro-methane in the vapor phase

Ultraviolet absorption cross-sections of trifluoro-bromo-methane (CF₃Br-Halon 1301), difluoro-dibromo-methane (CF₂Br₂-Halon 1202) and of difluoro-bromo-chloro-methane (CF₂BrCl-Halon 1211) are measured in the wavelength interval 172–304 nm for temperatures ranging from 210 to 295 K with uncertainties of between 2 and 4%. They are compared with previous measurements available at room temperature. Temperature effects are discussed and parametrical formulae are proposed to compute the absorption cross-sections for wavelengths and temperatures useful in atmospheric modelling calculations. Photodissociation coefficients are presented and their temperature dependence is discussed.