Spectroscopic Characterization of HOONO and its Binding Energy via Infrared Action Spectroscopy

via Infrared Action Spectroscopy Ilana B. Pollack, Ian M. Konen, Eunice X.J. Li, and Marsha I. Lester Department of Chemistry, University of Pennsylvania Philadelphia, PA 19104-6323 Abstract The trans-perp (tp) conformer of peroxynitrous acid (HOONO), a secondary product of the OH + NO2 reaction and a less stable isomer of nitric acid, has been identified by infrared action spectroscopy in the OH overtone region after being generated in a pulsed supersonic expansion. Rotational structure associated with the OH overtone band of tp-HOONO has been observed at 6971.4(1) cm (origin) and assigned by simulating its band structure using a transition dipole moment and rotational constants derived from ab initio theory. The highest observed OH product state, OH Π1/2 (v=0, J=13/2), sets an upper limit for the tp-HOONO binding energy of 16.8 kcal/mol, confirming previous estimates for the O-O bond energy of HOONO.