MILLIMETER-WAVE SPECTROSCOPY OF HYDRAZOIC ACID (HN3)

The rotational spectra for hydrazoic acid (HN 3 ), its isotopologues, and its vibrational satellites have been reexamined using millimeter-wave rotational spectroscopy in the range of 240-360 GHz. Treating sodium azide (NaN 3 ) or the commercially available singly 15 N-labeled NaN 3 with phosphoric acid or deuterated phosphoric acid yielded 6 different isotopologues. From these samples, we were also able to observe all of the isotopologues containing one additional 15 N at natural abundance. In total, we assigned rotational transitions to 14 different species; only H 15 N 3 and D 15 N 3 were not accessible. With the large number of rotational constants determined for these isotopologues, an excellent equilibrium structure determination was performed with CFOUR’s xrefit routine. This structure shows a bent azide sub-unit, and is in excellent agreement with the geometry optimization performed at the CCSD(T)/ANO2 level of theory. The Coriolis perturbation of the ground and first two vibrationally excited states of HN 3 will also be discussed.