Knowledge Bank

Methyl nitrite CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ONO is an important species in atmospheric chemistry involved in photochemical oxidation of volatile organic compounds. The \emph{cis} conformer (more stable by about 298 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$) has a high internal rotation potential barrier for the methyl group (731 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$) whereas for the trans conformer the barrier to internal rotation is extremely low (10 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$), leading to large internal rotation splittings. Only one high resolution infrared study was performed prior to this study. For the first time, high-resolution spectrum of CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ONO was recorded in the far infrared region (30-500 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$) using the synchrotron SOLEIL far-infrared beamline (AILES) and a Fourier transform (FT) spectrometer. Some 987 lines were assigned for the \emph{cis} isomer up to J=65 and combined with 66 previously recorded microwave lines. In addition, high-resolution spectrum of the $\nu 9$ band of the \emph{cis} isomer around 627.9 cm$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$ was also recorded using the FT spectrometer at LISA. New microwave data is currently recorded to improve the knowledge of both the \emph{cis} and \emph{trans} ground state parameters.