New line list for the v4 bands of the trans (790.117 cm-1) and cis (851.943 cm-1) conformers of nitrous acid (HONO): Accurate positions and absolute intensities

The goal of this work was to update and significantly improve the line lists that have been generated recently for 11 mu m bands of the trans- and cis- conformer forms of nitrous acid (HONO) [Armante R, Perrin A, Kwabia Tchana F, Manceron L. The v4 bands at 11 mu m: linelists for the trans- and cis- conformer forms of nitrous acid (HONO) in the 2019 version of the GEISA database. Molecular Physics 2021;120:e1951860]. That 2019 version of the 11 mu m line list was generated using the spectroscopic parameters that were available, at that time, in the literature. During the present study, we used high-resolution Fourier transform spectra recorded at 11 mu m to perform a large investigation of line positions and intensities for the v4 bands of the trans- and cis-conformer of HONO. The resulting set of experimental v4 (absolute) intensities and of 41 energy levels were used to determine, by least squares fit computations, improved position and intensity parameters for the v4 bands of the trans- and cisconformer of HONO. For trans-HONO, the v4 band appeared not to be perturbed, while for cis-HONO a weak high order B-type Coriolis, coupling together the 41 and 61 energy levels was evidenced for the first time. This new list is of potential interest for the IASI-NG (Infrared Atmospheric Sounding Interferometer - New Generation) instrument which will be launched on board the METOP-SG satellite in 2025.