Kinetic study of gas phase reactions of OH with CF 3 CH 2 OH, CF 3 CF 2 CF 2 CH 2 OH, and CHF 2 CF 2 CH 2 OH using LP-LIF method Y.N. Indulkar a, b , S. SenGupta b , S.B. Waghmode a , A. Kumar b , S. Dhanya b, * , P.D. Naik b a Department of Chemistry, University of Pune, Ganeshkhind, Pune 411 007, India b Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India article info Article history: Received 29 June 2011 Received in revised form 8 September 2011 Accepted 9 September 2011 Keywords: Fluoroalcohols OH radical Rate constants Tropospheric lifetime abstract The rate coefficients for the reactions of OH radicals with three fluoroalcohols, CF 3 CH 2 OH (k 1 ), CF 3 CF 2 CF 2 CH 2 OH (k 2 ), and CHF 2 CF 2 CH 2 OH (k 3 ), have been measured in the temperature range of 298e363 K, at a total pressure of w55 torr, using LP-LIF method. The kinetic parameters measured for CF 3 CH 2 OH, which is well studied, matches with the previous reports within error limits. The rate expression for k 2 is (1.54  0.80)  10 12 exp (765  170)/T), and for k 3 is (1.12  0.26)  10 12 exp (560  80)/T). Based on the above values of the rate coefficients, the tropospheric lifetimes with respect to removal by reaction with OH have been estimated to be 0.38 and 0.26 years for CF 3 CF 2 CF 2 CH 2 OH and CHF 2 CF 2 CH 2 OH respectively, supporting their potential use as HFC alternatives. The results are discussed along with the literature data on other fluoroalcohols. The present study is aimed to assess the effect of additional CF 2 groups and H atoms on tropospheric lifetime and global warming potential of fluoroalcohols. The results confirm that the rate coefficients at room temperature and activation energy parameters are independent of n, for the reaction of OH with fluoroalcohols of general formula CF 3 (CF 2 ) n CH 2 OH, which are potential CFC/HFC alternatives. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction The role of the chlorofluorocarbons (CFCs) in stratospheric ozone depletion through photolytic generation of Cl atom is a widely recognized problem (WMO Report, 2002). Since their industrial use is restricted by Montreal Protocol and its subsequent amendments, international efforts to find suitable alternatives have led to hydrofluorocarbons (HFCs) as probable substitutes of CFCs. However, their strong IR absorption and relatively long atmo- spheric lifetime classify them among the anthropogenic green- house gases, which are regulated by Kyoto Protocol. Recently, partially fluorinated alcohols (HFAs) have been identified as new generation of CFC alternative for applications such as cleaning of electronic components, refrigeration, and as carrier compounds for lubricants (Hurley et al., 2005). HFAs are expected to have higher chemical reactivity than HFCs due to the presence of the eOH group and therefore shorter atmospheric lifetimes. These HFAs could be removed via their reactions with OH, photolysis, wet deposition, and dry deposition in the atmosphere. Since these molecules absorb only in the short wavelength region of the solar spectrum (Salahub and Sandorfy, 1971), which is not available in the troposphere, their photolytic loss in troposphere is insignificant and the dominant loss processes are wet deposition (Chen et al., 2003a) and reaction with OH radicals. In HFAs with long fluori- nated chain, wet deposition is also expected to be insignificant, with tropospheric lifetime being solely dependent on the reaction with OH radical. Hence, the kinetic parameters of the reactions of OH with HFAs are essential to estimate their tropospheric lifetimes and to understand their impact on the environment and contri- bution toward global warming. In the present study, the rate coefficients of the reactions of OH radical with CF 3 CH 2 OH (1), CF 3 CF 2 CF 2 CH 2 OH (2), and CHF 2 CF 2 CH 2 OH (3) have been measured in the temperature range of 298e363 K, using laser photolysis-laser induced fluorescence (LP-LIF) technique. In the case of CF 3 CH 2 OH, the most studied molecule in this class of HFAs, there is a good agreement within the reported parameters, measured using different techniques (Wallington et al., 1988; Tokuhashi et al., 1999; Kovács et al., 2006; Hurley et al., 2004; Sellevåg et al., 2004) or estimated theoretically (Wang et al., 2007). The most recent recommendation of the rate coefficient at 298 K is 1.1 10 13 cm 3 molecule 1 s 1 and E a /R is 863 K (IUPAC). The rate coefficients at room temperature (k 298 ) for the reactions of OH with higher homologues of the HFAs with CH 2 OH end group, CF 3 (CF 2 ) n CH 2 OH, were found to be independent of the fluorinated * Corresponding author. E-mail address: sdhanya@barc.gov.in (S. Dhanya). Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.atmosenv.2011.09.022 Atmospheric Environment 45 (2011) 6973e6979