Millimeter-wave spectroscopy of highly nitrogenous molecules of potential astrochemical interest

A previously existing millimeter-wave absorption spectrometer was modernized and used in several rotational spectroscopy projects. The improvements to the apparatus are described briefly. This instrument has a nominal frequency range of 270-360 GHz, but strong transitions can often be observed throughout the extended range 235-450 GHz. One spectroscopic target was carbonyl diazide (OC(N3)2), a high-energy compound which can serve as a precursor to several other molecules of interest. A safe and efficient synthesis of carbonyl diazide from triphosgene and sodium azide is described. Pure rotational spectra were assigned for the ground vibrational state of two conformers of carbonyl diazide. Transitions from four vibrationally excited states of the syn-syn conformer of carbonyl diazide were also assigned, although local perturbations necessitated that some transitions be excluded from the non-linear least-squares-fitting. Preliminary attempts to pyrolize carbonyl diazide to form diazirinone (c-OCN 2) are described.;Hydrazoic acid (HN3) is a molecule of great spectroscopic interest which was also subjected to in-depth study. The rotational spectra for fourteen isotopologues of hydrazoic acid were assigned. The experimentally determined moments of inertia for these isotopologues were combined with ab initio (CCSD(T)/ANO2) vibration-rotation interaction corrections to obtain mixed theoretical/experimental values for the equilibrium moments of inertia. These equilibrium moments of inertia were used to make a highly redundant determination of the equilibrium structure of hydrazoic acid. The determined structure agrees with a CCSD(T)/cc-pCV5Z theoretical calculation to within 0.0002 A for the three bond distances and 0.12° for the two bond angles. The vibrationally excited states of hydrazoic acid and deuterated hydrazoic acid (DN3) have also been studied. For both isotopologues, seven vibrationally excited states are at low enough energy to be observable with the millimeter-wave spectrometer operating at room temperature. Numerous perturbations, both global and local, exist between the vibrational states. Work towards the understanding of these numerous perturbations is described. The goal of these efforts is to obtain a model which accurately and simultaneously predicts the transitions in the current extensive millimeter-wave dataset and in the large quantity of previously published high resolution FTIR data.;The appendices contain the published work relating to these projects.