A SHOCK-TUBE STUDY OF THE OH-]H2O+O REACTION(OH)

The rate coefficient for the reaction (1) OH + OH --> H2O + O has been determined in mixtures of nitric acid (HNO3) and argon in incident sh ock wave experiments. Quantitative OH time-histories were obtained by cw narrow-linewidth uv laser absorption of the R1(5) line of the A2SIG MA+ <-- X2PI(i) (0, 0) transition at 32606.56 cm-1 (vacuum). The exper iments were conducted over the temperature range 1050-2380 K and the p ressure range 0.18-0.60 atm. The second-order rate coefficient was det ermined to be k1 = 9.40 x 10(-5) T4.77 exp(+4570/T [K]) [cm3 mol-1 s-1 ] with overall uncertainties of +11%, -16% at high temperatures and +2 5%, -22% at low temperatures. By incorporating data from previous inve stigations in the temperature range 298-578 K, the following expressio n is determined for the temperature range 298-2380 K k1 = 3.57 x 10(4) T2.40 exp(+1063/T [K 1) [cm3 mol-1 s-1]. (C) 1994 John Wiley & Sons, Inc.