The UV-B (broadband 280-320 nm, peak λ = 313 nm) and UV-C (λ = 254 nm) initiated photolytic oxidation of 1,1-difluoroacetone (CF2HC(O)CH3) and 1,1,1-trifluoroacetone (CF3C(O)CH3) was studied as a function of total pressure using smog chamber techniques. The UV spectrum of CF2HC(O)CH3 and CF3C(O)CH3 are reported; the former for the first time. The UV-B and UV-C photolysis rates were measured relative to that of CH3C(O)CH3. The approximate UV-B (313 nm) quantum yield for CF2HC(O)CH3 and CF3C(O)CH3 were determined as 0.03 and 0.007. At 254 nm, the overall quantum yields for CF2HC(O)CH3 and CF3C(O)CH3 were determined as (1.11 ± 0.13) and (0.69 ± 0.08), respectively, at 700 Torr, (298 ± 1) K, independent of diluent gas. This is the first chamber study of the photolysis of CF2HC(O)CH3 and CF3C(O)CH3. The measured yields of HCOF, COF2 (and CO) suggest that photolysis of CF2HC(O)CH3 and CF3C(O)CH3 produces CF2H and CF3 radicals, respectively, both in yields of unity. Additional products identified include CH3OH and HCHO. Pressure-dependent decomposition pathways were identified in the UV-C photolysis and overall photolysis mechanisms are proposed. Finally, the atmospheric photolysis-lifetimes of CF2HC(O)CH3 and CF3C(O)CH3 were estimated based on a Tropospheric Ultraviolet Visible (TUV) model calculation.
Andersen et al. (Mon,) studied this question.