Chlorine nitrate: Kinetics of formation by ClO+NO2+M and of reaction with OH

摘要

Kinetic studies by the dischargendash;flow technique are reported. For ClONO2formation fromT=250ndash;365 K, ClO decays in excess NO2are monitored by conversion of ClO to Cl followed by resonance fluorescence detection at 134.7 nm. For OH reaction overT=246ndash;387 K, pseudohyphen;firsthyphen;order OH decays are observed directly by OHhyphen;resonance fluorescence. The recombination reaction (1) is near its low pressure, thirdhyphen;order limit withk1= (0.83plusmn;0.12) times;10minus;31cm6sminus;1at 300 K for M=He and (1.52plusmn;0.23) times;10minus;31cm6sminus;1at 297 K for M=N2. Thek1,Hetemperature dependence corresponds toTminus;3.15. These results are in good agreement with those of other studies. A temperaturehyphen; and pressurehyphen;dependent, empirical rate constant expression for stratospheric modeling calculations is proposed. The rate constantk2for the OH reaction is found to be (1.19plusmn;0.10) times;10minus;12thinsp;explsqb;(minus;333 plusmn;22)/Trsqb; cm3sminus;1, i.e., (3.93plusmn;0.11) times;10minus;13at 295 K. The results are compared with other measurements and their significance for stratospheric processes is discussed.