Abstract: | The rate coefficient for the reaction has been determined in mixtures of nitric acid (HNO3) and argon in incident shock wave experiments. Quantitative OH time-histories were obtained by cw narrow-linewidth uv laser absorption of the R1(5) line of the A2 σ+ ← X2 Πi (0,0) transition at 32606.56 cm?1 (vacuum). The experiments were conducted over the temperature range 1050–2380 K and the pressure range 0.18–0.60 atm. The second-order rate coefficient was determined to be with overall uncertainties of +11%, ?16% at high temperatures and +25%, ?22% at low temperatures. By incorporating data from previous investigations in the temperature range 298–578 K, the following expression is determined for the temperature range 298–2380 K © 1994 John Wiley & Sons, Inc. |