Nitric oxide chemiexcitation occurring in the reaction between metastable nitrogen atoms and oxygen molecules

Abstract

The infrared emission spectrum of the NO Δv=1 bands, chemiexcited in the reaction between metastable atomic nitrogen and molecular oxygen, has been studied at temperatures of 90–180 K and pressures near 5×10−6 atm. It is concluded that the observed radiation corresponds to an NO vibrational distribution created solely by the chemical reaction, unaffected by any relaxation process(es). Relative rate constants for production of NO into individual vibrational levels are found to be very nearly constant for levels v=1–7 and decrease monotonically for levels v=8–12. The average degree of excitation is about 4.5 vibrational quanta per NO molecule, and, assuming that N(2P) atoms play a negligible role, it is determined that 27% of the N(2D)+O2 exothermicity is converted to vibrational excitation of the nitric oxide product. Both the nature of the distribution and the results of a surprisal analysis suggest that those reactions which produce NO in levels higher than v=7 may also be producing O(1D).

Estimation of atomic oxygen concentrations from measured intensities of infrared nitric oxide radiation

“…Similar estimations were obtained in Green et al (1984). Rawlins et al (1989) have used the technique which has been employed in Kennealy et al (1978). The principal dierence between their investigation and an earlier study is the more detailed analysis of the contribution of N 2 P O 2 reaction in the observed NOv distribution.…”

“…9 and 10 in Rawlins et al, 1989). The ®nal conclusions of Rawlins et al (1989) are in signi®cant disaccord with the results of Kennealy et al (1978), and Green et al (1984) showing much higher vibrational excitation of NO on levels v 1±3.…”

“…Since the estimations of surprisal parameter k 1 for O 1 D branch of the reaction (2a) by Kennealy et al (1978) and Rawlins et al (1989) have given dierent values (À2X1 and À6X25, respectively), the parameter is varied in our calculation from À7 to À2. The parameter for O 3 P branch used according to the magnitude of Rawlins et al (1989).…”

“…The surprisal analysis of infrared emission spectrum of the NO Dv 1 bands in Kennealy et al (1978) gave the surprisal parameter k 1 À2X1 for the O 1 D branch of the reaction (2a). Similar estimations were obtained in Green et al (1984).…”

“…The branching ratios of the reactions (2a,2b) were measured in Kennealy et al (1978), Green et al (1984) and Rawlins et al (1989). The experimentally observed NOv distributions were examined with the aid of surprisal theory (Bernstein and Levine, 1975;Nesbet, 1981) based on information theory.…”