First high-resolution analysis of the 4ν 1+ν 3 band of nitrogen dioxide near 1.5 μm

Abstract

The high-resolution absorption spectrum of the 4ν 1+ν 3 band of the 14N 16O 2 molecule was recorded by CW-Cavity Ring Down Spectroscopy between 6575 and 6700 cm −1. The assignments involve energy levels of the (4,0,1) vibrational state with rotational quantum numbers up to K a=8 and N=48. A large majority of the spin-rotation energy levels were reproduced within their experimental uncertainty using a theoretical model which takes explicitly into account the Coriolis interactions between the spin-rotational levels of the (4,0,1) vibrational state and those of the (4,2,0) and of (0,9,0) dark states, the anharmonic interactions between the (4,2,0) and (0,9,0) states together with the electron spin-rotation resonances within the (4,0,1), (4,2,0) and (0,9,0) states. Precise vibrational energies, rotational, spin-rotational, and coupling constants were determined for the {(4,2,0), (0,9,0), (4,0,1)} triad of interacting states. Using these parameters and the value of the transition dipole-moment operator determined from a fit of a selection of experimental line intensities, the synthetic spectrum of the 4ν 1+ν 3 band was generated and is provided as Supplementary Material.