Knowledge Bank

A ro-vibrational analysis of the C-type $\nu 8$ fundamental band of $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}C1ONO2$ as well as the hot band, $\nu 8+\nu 9-\nu 9$, has been carried out using a Fourier-transform infrared spectrum of natural chlorine nitrate. This spectrum was recorded with a resolution of $0.00094cm-1$ at a temperature of 190 K. Accurate upper state constants have been determined for both bands including the following band centers: $\nu 0(\nu 8)=711.20763(9)$ and $\nu 0(\nu 8+\nu 9-\nu 9)=714.9050(12)cm-1$. These constants have been used, together with a transition moment operator which takes into account the observed Herman-Wallis effect, to successfully model the experimental spectrum. Moreover the constants of the $8191$ state have been used to model the $\nu 8+\nu 9$ band, allowing us to assign nearly 100 Q-branch transitions and, therefore, to determine the band center of the $\nu 8+\nu 9$ band, $\nu 0(\nu 8+\nu 9)=838.6269(15)cm-1$. Consequently we are able for the first time to obtain a precise band center of $\nu 9:\nu 0(\nu 9)=123.7219(20)cm-1$. Finally this establishes unambiguously that the band at $714.9cm-1$ previously attributed to $\nu 5+\nu 7-\nu 9$ is actually the $\nu 8+\nu 9-\nu 9$ hot band.