A study of the IR and UV-Vis absorption cross-sections, photolysis and OH-initiated oxidation of CF3CHO and CF3CH2CHO

Abstract

Infrared and ultraviolet-visible absorption cross-sections, effective quantum yields of photolysis and OH reaction rate coefficients for CF3CHO and CF3CH2CHO are reported. Relative rate measurements at 298(2) K and 1013(10) hPa, give k(OH + CF3CHO)/k(OH + CH3CH3) = 2.00(13), k(OH + CF3CH2CHO)/k(OH + CH3CH2OH) = 1.21(5) and k(OH + CF3CH2CHO)/k(OH + HC(O)OC2H5) = 3.51(9) (2σ). The effective quantum yield of photolysis was measured under pseudo-natural conditions in the European simulation chamber, Valencia, Spain (EUPHORE). Over the wavelength range 290–400 nm, the effective quantum yields of photolysis for CF3CHO and CF3CH2CHO are less than 2 × 10−2 and 4 × 10−2, respectively. The tropospheric lifetimes are estimated to be: τOH(CF3CHO) ∼ 26 days; τphotol(CF3CHO) > 27 days; τOH(CF3CH2CHO) ∼ 4 days; τphotol(CF3CH2CHO) > 15 days.