Knowledge Bank

The spectra of all 3 fundamental bands and 2 overtone bands, $2\nu 1$ and $2\nu 3$, of OClO, have been obtained with a resolution of $0.004-0.006cm-1$. The $ClO2$ was prepared by flowing a mixture of $10zCl2$ in He at a total flow rate of $1cm3/sec$ and 50 Torr total pressure through a glass tube filled with = 50 g of $NaCIO2$. The $ClO2$ flowed directly into a multiple pass absorption cell and was diluted with a He flow. The concentration of $ClO2$ was measured using the UV absorption spectrum. The total path length was 97.3 m and the total pressure in the absorption cell was 1.5 Torr. The unpaired electron of OClO in its ground electronic state $(X2B1)$ gives rise to a weak coupling between the electronic spin and the overall rotation, and all the ro-vibronic transitions are doubled. An effective Hamiltonian which includes the corresponding interaction terms is necessary to account for the spectrum. A program has been written in which the Hamiltonian matrix is given using symmetric top basis functions times electronic spin functions which are appropriate for Hund's case (b). Quartic and sextic centrifugal distortion terms, as well as spin-rotation terms are explicitly treated in the model. At this point, the $\nu 1$ and $\nu 2$ bands have been assigned. The data for the $\nu 1$ band include transitions up to $Ka=20$ and $N=45$ for the $\mathrm{<mrow\; data-mjx-texclass="ORD">35</mrow>}Cl$ species and up to $Ka=18$ and $N=34$ for the $\mathrm{<mrow\; data-mjx-texclass="ORD">37</mrow>}Cl$ species. The data for the weaker and more blended $\nu 2$ band are somewhat more limited. These data have been combined with extensive microwave $data1$ to obtain an improved set of spectroscopic constants. The results are in good agreement with a laser Stark $study2$ on the $\nu 1$ band.