Rotational spectra of hydrazoic acid

•390 new rotational transitions of hydrazoic acid were measured and assigned.•Analysis of the rotational level crossing of several vibrational states.•Higher Ka values transition frequencies were included in the analysis.•Determination of rovibrational parameters of the ground and two vibrationally excited states.

Hydrazoic acid is a quasi-linear molecule with typical strong perturbations among rotational levels in different vibrationally excited states. The rovibrational interactions among the ground and the two lowest vibrationally excited states ν5 and ν6 make the line assignments very complicated. Overall 446 new rotational transitions were measured and assigned to rovibrational quantum numbers. This new dataset contains 194 transitions from the ground state, 160 and 92 transitions from the vibrationally excited ν5 and ν6 states, respectively. The rotational data set is extended up to Ka = 8 for the ground state, Ka = 7 for ν5, and Ka = 3 for ν6. The frequencies of these new rotational lines, along with the data from previous submillimetre and infrared studies were quantitatively analysed. The level crossings among ground and vibrationally excited ν5 and ν6 states and the corresponding rovibrational interactions were described in detail.

Graphical abstractDownload high-res image (110KB)Download full-size image