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

Abstract

Articles you may be interested inHigh-resolution laser spectroscopy and magnetic effect of the B ̃ 2E′ ← X ̃ 2A2′ transition of 14NO3 radical Electronic states, conical intersections, and spin-rovibronic spectroscopy of the nitrogen oxide sulfide radical J. Chem. Phys. 138, 104318 (2013); 10.1063/1.4794313High-resolution cavity ringdown spectroscopy of the jet-cooled ethyl peroxy radical C 2 H 5 O 2Time-resolved infrared diode laser spectroscopy of the ν1 band of the iron carbonyl radical (FeCO) produced by the ultraviolet photolysis of Fe(CO)5We have analyzed the near-infrared band of NO 3 observed at 7602 cm Ϫ1 by using diode laser spectroscopy. Most of the spectral lines were recorded using source-frequency modulation. Zeeman modulation was found useful in selectively detecting some Q branch lines, which provided us with a clue to the assignment of the observed spectra. The band satisfied selection rules for a parallel band and was thus ascribed to a 2 A 1 Љ -2 A 2 Ј vibronic component associated with the 2 EЉ -X 2 A 2 Ј electronic transition, namely, to a transition from the ground vibronic state to the A 1 Љ vibronic state resulting from excitation of the degenerate in-plane bending mode in the 2 EЉ electronically excited state manifold. The band was almost free of perturbations, except for some Kϭ6 lines. The least-squares analysis of 581 assigned lines led to molecular parameters of the upper state, where ground-state parameters were fixed to those obtained from the infrared study previously reported ͓K.Kawaguchi, E. Hirota, T. Ishiwata, and I. Tanaka, J. Chem. Phys. 93, 951 ͑1990͔͒. The upper-state B rotational constant gave the effective N-O distance of 1.271 Å, which is to be compared with 1.240 Å in the ground vibronic state. The ⑀ bb spin-rotation interaction constant of the upper state was close in magnitude to that in the ground vibronic state, but of opposite sign. This observation indicates that the spin-rotation interaction is primarily caused by that between the 2 EЉ excited and the ground electronic states.

Conflicting Observations Resolved by a Far IR and UV/Vis Study of the NO3 Radical

“…[4,5] Numerous spectroscopic studies have sought to obtain the equilibrium symmetry and the assignment of the vibrational transitions in the ground electronic state. Important recent studies include: 1) photoelectron (PE) spectroscopic studies of both the nitrate anion [6,7] and the NO 3 radical, [8] 2) laser-induced fluorescence (LIF) spectra of the nitrate radical, [9,10] as well as a recent reanalysis of the vibronic levels obtained from these spectra, aided by non-adiabatic computations, [11] 3) the analysis of high-resolution diode laser and FTIR gas phase spectra which were obtained in the region 700 to 1520 cm À1 , [12,13] and later extended to 1300-2800 cm À1 [14][15][16] and to the near infrared, [17] and 4) a neonmatrix FTIR study on NO 3 in the range from 450 to 6000 cm À1 . [18] From the analysis of the recent spectra, D 3h symmetry was determined for the free NO 3 radical in the X $ 2 A 2 ' ground state.…”

On the vibronic level structure in the NO3 radical : Part III. Observation of intensity borrowing via ground state mixing

“…3 Optical characterization of this state is complicated because the X-A electronic transition is forbidden by dipole selection rules; indeed, the first observation of a vibronically allowed nearinfrared transition at 7602 cm À1 was not reported by Hirota and coworkers until six years later. 4 In addition, the à 2 E 00 state is subject to the first-order Jahn-Teller effect, which distorts the equilibrium geometry from the idealized D 3h structure to a pair of three-fold equivalent C 2v geometries, which have There is a general consensus that the equilibrium geometry of the 2 B 1 state has two short and one long NO bonds and an ONO (short-short) bond angle of about 1301, and that the pseudorotation barrier is in the range 1000-1500 cm À1 . 5,6 The spectroscopy of the à 2 E 00 state has rather recently been expanded significantly by the work in one of our laboratories, the preliminary analysis of which was reported in ref.…”

“…2 (4) where the leading term vanishes and the intensity comes from the second contribution. Note that while this treatment is similar to the ubiquitous upper state borrowing (in that the only difference is in the side of the integral which is expanded in the quasidiabatic basis) and is clearly valid from a quantummechanical point of view, the idea that a vibronic transition is lent intensity by mixing of the ground electronic state with another state is not particularly common in electronic spectroscopy.…”

Near-infrared diode laser spectroscopy of the HCSi radical

“…The Doppler-limited rotationally resolved near-infrared absorption spectra were recorded by using the diode laser spectrosopic system designed for the study of radicals, which was essentially equivalent to that described previously [7][8][9]. The specifications in the present investigation are summarized as follows:…”