Atmospheric chemistry of CF3CHO, C2F5CHO, C3F7CHO, C4F9CHO, CF3CH2CHO and C6F13CH2CHO: UV Absorption spectra and quantum yields for photolysis at 254 and 308 nm over the temperature range 249-297K.

M.S. CHIAPPERO; F.E. MALANCA; G.A. ARGÜELLO; S.T. WOOLDRIDGE; M.D. HURLEY; T.J. WALLINGTON; R.L. WATERLAND; R.C. BUCK

JOURNAL OF PHYSICAL CHEMISTRY A

American Chemical Society

Lugar: EEUU; Año: 2006 vol. 110 p. 11944 - 11953

1089-5639

The UV absorption spectra of CF3CHO, C2F5CHO, C3F7CHO, C4F9CHO, CF3CH2CHO, and C6F13CH2CHO were recorded over the range 225-400 nm at 249-297 K. CxF2x+1CHO and CxF2x+1CH2CHO have broad absorption features centered at 300-310 and 290-300 nm, respectively. The strength of the absorption increases with the size of the CxF2x+1 group. There was no discernible (<5%) effect of temperature on the UV spectra. Quantum yields for photolysis at 254 and 308 nm were measured. Quantum yields at 254 nm were 0.79±0.09 (CF3CHO), 0.81±0.09 (C2F5CHO), 0.63±0.09 (C3F7CHO), 0.60±0.09 (C4F9CHO), 0.74±0.08 (CF3CH2CHO), and 0.55±0.09 (C6F13CH2CHO). Quantum yields at 308 nm were 0.17±0.03 (CF3CHO), 0.08±0.02 (C4F9CHO), and 0.04±0.01 (CF3CH2CHO). The quantum yields decrease with increasing size of the CxF2x+1 group and with increasing wavelength of the photolysis light. The photolysis quantum yield at 308 nm for CF3CHO measured here is a factor of at least 8 greater than that reported previously. Photolysis is probably the dominant atmospheric fate of CxF2x+1CHO (x=1-4) and is an important fate of CxF2x+1CH2CHO (x = 1 and 6). These results have important ramifications concerning the yield of perfluorocarboxylic acids in the atmospheric oxidation of fluorotelomer alcohols.