资源环境科技发展态势分析平台

Pulsed laser excitation of NO2 (532-647 nm) or NO3 (623-662 nm) in the presence of H2O was used to initiate the gas-phase reaction NO2* + H2O -> products (Reaction R5) and NO3* + H2O -> products (Reaction R12). No evidence for OH production in Reactions (R5) or (R12) was observed and upper limits for OH production of k(5b)/k(5) < 1 x 10(-5) and k(12b)/k(12) < 0.03 were assigned. The upper limit for k(5b)/k(5) renders this reaction insignificant as a source of OH in the atmosphere and extends the studies (Crowley and Carl, 1997; Carr et al., 2009; Amedro et al., 2011) which demonstrate that the previously reported large OH yield by Li et al. (2008) was erroneous. The upper limit obtained for k(12b)/k(12) indicates that non-reactive energy transfer is the dominant mechanism for Reaction (R12), though generation of small but significant amounts of atmospheric HOx and HONO cannot be ruled out. In the course of this work, rate coefficients for overall removal of NO3* by N-2 (Reaction R10) and by H2O (Reaction R12) were determined: k(10) = (2.1 +/- 0.1) x 10(-11) cm(3) molecule(-1) s(-1) and k(12) = (1.6 +/- 0.3) x 10(-10) cm(3) molecule(-1) s(-1). Our value of k(12) is more than a factor of 4 smaller than the single previously reported value.