Knowledge Bank

$CINO2$ is a molecule of potential stratospheric and tropospheric importance, formed by heterogeneous reactions on polar stratospheric clouds and sea-salt particles. In 1994, high-resolution infrared spectra of $ClNO2$ were measured and analyzed in the $500-2500cm-1$ $rangeg$. However, up to now, no high-resolution absorption spectra of the $\nu 3$ and $\nu 3$ fundamental bands of $ClNO2$ in the far-infrared region were reported, except for microwave observation of a few transitions in the excited vibrational $statesh$. In the present study, absorption spectra in $300-500cm-1$ range were recorded at resolutions of up to $0.0017cm-1$, using the Bruker IFS-120HR FTS at University of Giessen. Using these spectra, nearly 2000 transitions of the a-type $\nu 3$ band around 370 $cm-1$ were assigned. The b-type $\nu 3$ band around $411cm-1$ is too weak to be observed, in agreement ab-initio predictions. However, the ($\nu 2-\nu 3$) a-type difference band was observed and could be used to confirm rotational constants of both vibrational states.