Mechanism of chemiluminescent reaction between nitric oxide and ozone

Abstract

The absolute intensity and quenching constants of the NO2 emission in the chemiluminescent reaction between nitric oxide and ozone have been determined using a large capacity-flow reactor at low pressures. These studies have confirmed the mechanism previously proposed :The rate constants of the primary steps are kl, = (7.6f1-5)x 1011 exp (-4180f300/RT) and klb= (4.3 f1.0) x 1011 exp (-2330f150/RT) cm3 mole-1 sec-1. The half-quenching pressures (k2/k3m) of electronically excited NO2 produced are : Ar = 13.03~ 1.0 p, 0 2 = 8-3f0.5 p, NO = 5.2f0.3 p, NO2 = 3.7f0-1 p. The detailed mechanism of reactions (la) and (lb) is discussed.

Discovery of the FeO orange bands in the terrestrial night airglow spectrum obtained with OSIRIS on the Odin spacecraft

“…Accordingly, attempts to detect faint emissions in the night airglow spectrum are more likely to succeed at lower latitudes. The chemiluminescent NO + O 3 → NO 2 * + O 2 reaction also produces emission in the 600 nm region [Clough and Thrush, 1967] and can potentially contribute to the airglow signal, although Bates [1993] concluded that for this mechanism "the contribution to the nightglow is inappreciable".…”

Interferences in photolytic NO<sub>2</sub> measurements: explanation for an apparent missing oxidant?

“…The photons emitted are detected by a cooled photomultiplier tube (PMT) with the sample under low pressure (to maximize the fluorescence lifetime of the NO * 2 ) in order to yield a signal which is linearly proportional to the number density of NO in the sample gas (Fontijn et al, 1970). Quenching of the NO 2 excited state occurs due to a range of atmospheric compounds (N 2 , Ar, CO, CO 2 , CH 4 , O 2 , He, H 2 , and H 2 O) (Clough and Thrush, 1967;Drummond et al, 1985;Zabielski et al, 1984). Quenching is minimized by operating at high vacuum to reduce collision probability.…”

“…However, probably the most extensively used approach has been based on the chemiluminescent reaction between NO and O 3 . This exploits the reaction between NO and O 3 (Reaction R6), which generates a electronically excited NO * 2 ( 2 B 1 ) molecule which decays to its ground state through the release of a photon (Reaction R7) (Clough and Thrush, 1967;Clyne et al, 1964).…”

Fluorescence Methods

“…) <1 s following excitation, the emission spectrum of NO 2 exhibits vibrational structure at pressures below ∼10 m torr (Donnelly et al, 1979). At longer times or higher pressures, the emission spectrum resembles a broad peak centred in the near-IR due to efficient stepwise vibrational relaxation of the excited electronic state (Clough & Thrush, 1967, Mazely et al, 1994, Patten et al, 1990. The excited state lifetime of NO 2 ∼ 100 s is much longer than expected based on its integrated absorption cross section and is a strong function of excitation wavelength, pressure, and spectral region observed during measurement (Donnelly & Kaufman, 1978, Patten et al, 1990, Sackett & Yardley, 1972.…”