Knowledge Bank

Methyl nitrite (CH$3$ONO) contains a mixture of cis and trans rotational isomers. As in the $\nu 8$ and $\nu 9$ vibrations of the cis form, the $\nu 3$ vibration is not too congested, consistent with the high barrier to rotation of the methyl group in the cis form. The $\nu 3$, with an origin at 1620. cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$, has been assigned by previous workers to the N=O stretch of the cis conformer and hot bands are also present in this region. In this study, a spectrum taken at 0.0015 cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ resolution on the PNNL IFS120/HR in a 20 cm cell was used to assign more than 300 A-type transitions of the cis $\nu 3$ between 1600 and 1650 cm $\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ and a set of excited state constants was determined.