The 7390 Å band of NO₂, a vibronically-induced transition within the ground state manifold

Abstract

About 160 rotational lines in the region 7370–7410 Å in the electronic spectrum of NO 2 have been assigned from high dispersion grating spectra. The lines form the K = 0,1, and 2 sub-bands of a perturbed parallel band where the upper state A rotational constant is about 17 cm −1 . In a diabatic representation the band can be considered as a transition within the ground state manifold, which obtains its intensity by vibrational momentum coupling from a nearby band of the [Formula: see text] electronic transition; its vibrational assignment is 2 13 1 – 000. Comparison with the spectrum of 15 NO 2 shows that the nearby à 2 B 2 level has quite a small amount of vibrational energy, which is not inconsistent with the assignment by Brand, Chan, and Hardwick that the (0, 0) band of the [Formula: see text] transition is at 8350 Å. The implications of the electron spin–rotation parameters and the intensity of the 7390 Å band are discussed.