# A PARTIAL ANALYSIS OF HONO BANDS BETWEEN 750 AND $1300 cm^{-1}$

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 Title: A PARTIAL ANALYSIS OF HONO BANDS BETWEEN 750 AND $1300 cm^{-1}$ Creators: Chan, W. H.; Mathews, C. W.; Nordstrom, R. J. Issue Date: 1976 Publisher: Ohio State University Abstract: Nitrous acid (HONO) has been proposed to be a significant source of HO-radicals in sunlight-irradiated, $NO_{X}$-rich exhaust gases $environments.^{1}$ To facilitate the identification and detection of this molecule in the atmosphere, moderately high resolution ($0.125 cm^{-1}$) spectra were obtained in the mid-IR region by Fourier transform spectroscopy using a path length of 43 m and a nitrous acid concentration of $< 5 \times 10^{-5}$ atm. The $\nu_{4}$ bands of both the trans- and the cis-isomers (at 790 and $852 cm^{-1}$, respectively) and the $\nu_{3}$ band of the trans-isomer (at $1263 cm^{-1}$) are A-type transitions and are mildly degraded to higher energies. The positions and relative intensities of these bands are in agreement with the assignments by McGraw $et al.^{2}$ A partial rotational analysis of each of these bands has been carried out using Watson’s Hamilton and the lower state constants given by Cox $et al.^{3}$ A much weaker band of HONO has also been observed near $1068 cm^{-1}$. This band exhibits B-type structure and it is rather strongly degraded to lower energies. A preliminary analysis of the $^{P}Q$ and $^{r}Q$ heads suggests that it is an overtone band due to $2\nu_{6}$ of the trans-isomer. Description: $^{1}$W. H. Chan, R. J. Nordstrom, J. G. Calvert, and J. H. Shaw, Chem. Phys. Lett. 37 (3) 441 (1976). $^{2}$G. E. McGraw, D. L. Bernitt, and I. C. Hisatsune, J. Chem. Phys. 45, 1392 (1966). $^{3}$A. P. Cox, A. H. Brittain, and D. J. Finnigan, Trans. Faraday Soc. 67, 2179 (1971). This work was supported, in part, by the U. S. Environmental Protection Agency. $^{1}$R A. Toth and J. S. Margolis, J. Mol. Spectrosc. 55, 229 (1975). This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract Number NAS7-100, sponsored by the National Aeronautics and Space Administration. Author Institution: Departments of Chemistry and Physics, The Ohio State University URI: http://hdl.handle.net/1811/9584 Other Identifiers: 1976-FC-6