CAVITY RINGDOWN SPECTROSCOPY OF CIS-CIS HOONO AND THE HOONO/HONO2 BRANCHING RATIO IN THE REACTION OH + NO2 + M

Author Institution: California Institute of Technology; NASA Jet Propulsion Laboratory, California Institute of Technology; Department of Chemistry, Washington state University; Department of Chemistry, Purdue UniversityThe termolecular association reaction OH + NO2 + M was studied in a low pressure discharge flow reactor, and both HONO2 and HOONO products were detected by Infra-Red Cavity Ringdown Spectroscopy (IR-CRDS). The absorption spectrum of the fundamental $\nu 1$ band of the cis-cis isomer of HOONO (pernitrous or peroxynitrous acid) was observed at $3306 cm^{-1}$, in good agreement with matrix isolation studies and ab initio predictions. The rotational contour of this band was partially resolved at 1 $cm^{-1}$ resolution and matched the profile predicted by ab initio calculations. The integrated absorbances of the $\nu 1$ bands of the cis-cis HOONO and HONO2 products were measured as a function of temperature and pressure