tmospheric Chemistry of Perfluoroaldehydes (CxF2x+1CHO) and Fluorotelomer Aldehydes (CxF2x+1CH2CHO): Quantification of the Important Role of Photolysis

MALISA S. CHIAPPERO, FABIO E. MALANCA, GUSTAVO A. ARGUELLO, STEVEN T. WOOLDRIDGE, MICHAEL D. HURLEY, JAMES C. BALL, TIMOTHY J. WALLINGTON,, ROBERT L. WATERLAND, AND ROBERT C. BACK

JOURNAL OF PHYSICAL CHEMISTRY A

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.