Kinetic Studies of the Reaction between NO₃and OClO atT= 300 K andP= 2−8 Torr

Abstract

The kinetics of the reaction between the radicals NO 3 and OClO have been investigated at low pressure and room temperature using three laboratory techniques: discharge stopped-flow, slow-flow, and discharge-flow. In all types of experiment, strong evidence was found to suggest that reaction between the two species occurred on the walls of the reaction cell and led to the release of ClO into the gas phase. No evidence was found for the occurrence of the homogeneous reaction NO 3 + OClO f products, and an upper limit for the rate coefficient for this process of 6 × 10 -17 cm 3 molecule -1 s -1 was determined. These experimental results are in disagreement with those of a previous study and suggest that this gas-phase reaction is unlikely to be of atmospheric importance even in the regions of the nighttime stratosphere where both species coexist.Kinetic Studies of the Reaction between NO 3 and OClO

Near-infrared band of the nitrate radical NO3 observed by diode laser spectroscopy

“…They thus clearly demonstrated that the ground vibronic state conformed nicely to the structure of D 3h symmetry. This conclusion was supported by Friedl and Sander, 21 who, in addition to 3 , observed the 2 out-ofplane bending band at 762 cm Ϫ1 by using high-resolution Fourier-transform infrared spectroscopy. Hirota et al 22 interpreted some anomalous features of spectroscopic constants observed in the 3 state in terms of vibronic interactions of this vibrational state with excited electronic states of 2 EЈ symmetry.…”

“…On the other hand, the second-order term lifts the degeneracy of the 2 A 1 Љ and 2 A 2 Љ levels by shifting them by ϩ2k 2 and Ϫ2k 2 , respectively, but again the 2 EЉ level is not affected by the interaction. Spin-orbit interaction does not seem to play an important role in the 2 EЉ electronic state, because, if it makes even a small contribution, it affects the rotational spectra substantially, as exemplified in our previous study on the 3 band in the ground electronic state. 20 In contrast with the case of this 3 band, we do not observe any anomalies in the spinrotation splitting in the present vibronic band.…”

“…The N-O bond length is thus elongated from 1.240 Å in the ground state to 1.271 Å in the upper state. It is interesting to note that Weaver et al 27 simulated the 1 progressions in the photodetachment spectra corresponding to the transitions from the NO 3 Ϫ anion ground state to the ground and the 2 EЉ electronic states of the neutral NO 3 and thus estimated the changes in the N-O bond length by these transitions to be 0.03 and 0.07 Å, respectively. This result means that the N-O bond length in the 2 EЉ excited state is 1.28 Å, which agrees closely with the present result.…”

“…This observation is discussed below. Series II consists of N, Kϭ4,3; 7,6; 10,9;..., and Series III of N, Kϭ5,3;8,6;11,9; ... . These assignments were consistent with the assumption that the lower state was common with those of most infrared bands, namely, the ground vibronic state.…”

“…At an initial stage, the visible absorption spectrum was employed to detect and monitor NO 3 both in laboratory and ambient air. [1][2][3] Some vibrational structures were tentatively assigned, 4 but none of the bands were rotationally resolved even at highest resolution then available. 5 In 1983 two groups 6,7 concurrently reported laser-induced fluorescence ͑LIF͒ and dispersed fluorescence spectra of NO 3 in the visible region.…”