First experimental observation of vibrationally excited NO 2+(X 2Σ +, A 2Π)

Abstract

Transitions among the three lowest X 2Σ +, A 2Π and B 2Σ + bound states of NO 2+ are investigated by means of high-resolution (0.08–0.35 eV fwhm) translational energy spectroscopy (TES). As well as electronic transitions between the ground and the two lowest electronic excited states, the spectra clearly show two distinct groups of vibrational transitions having average vibrational spacings of 0.22 and 0.17 eV respectively. The two groups of vibrational levels are assigned to transitions involving NO 2+ (X 2Σ +, 7 ⩾ν⩾3 ▪ν=0) and (A 2Π, 6⩾ν⩾3←ν=0. The measured vibrational spacings are in accord with the values of 0.159 and 0.242 eV predicted by the latest ab initio calculations.