N 2 O Dissociation behind reflected shock waves

The dissociation of N 2 O/Ar mixtures, with and withoutadded CO, has been studied by monitoring both infrared and ultraviolet emissions behind reflected shock waves. Initial temperatures ranged from 1850 to 2535°K, and the total concentrations were 1.94–2.40 × 10 18 molecule/cm 3 . The infrared emission, corrected if necessary for CO, was observed to decay exponentially, and an apparent rate constant K app was obtained. Addition of CO had no effect upon k app and all the data can be described by the followingArrhenius parameters (in units of cm 3 /molecule.sec): log A =−9.31±0.12 and E A =219.1±5.2 kJ /mole. Ultraviolet emission data, in runs with added CO, indicate that the atomic oxygen concentration reached a constant value at t < 600 μsec for T 0 > 2050°K. Numerical integration of the mechanismallowed comparison of calculated and observed parameters relating to both infrared and ultraviolet data. A consistent fit to these data was obtained with k 1 =1.3×10 −9 exp (−238 kJ/ RT ) and k 2 = k 3 =1.91×10 −11 exp(−105 kJ/ RT ). The concentration of atomic oxygen produced by N 2 O dissociation is shown to be a sensitive function of k 1 through k 3 . Upper limits are also set for the rate constants of the following reactions: