Knowledge Bank

The methoxy radical has been the subject of numerous theoretical and experimental spectroscopic studies. This interest arises, in part, because of its importance in combustion systems and in the chemistry of the upper atomossphere. Perhaps more importantly the spin-orbit splitting and Jahn-Teller distortions of its $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}E$ electronic ground state are predicted to be signignificant. Thus this radical provides an excellent test of our current understanding of the interaction between these effects. We have produced rotationally cold methoxy radicals by 248 cm photolysis of methyl nitrite ($CH3ONO$) seeded in a helium free-jet expansion. A laser excitation spectrum of the $A¯\leftarrow X¯$ system was recorded with a frequency-doubled dye laser and showed completely resolved rotational structure. Detailed information about the ground-state vibrational structure has also been obtained by dispersing the fluorescence from laser-excited single rovibrational level of the $A¯2A1$ state. The implications of these spectral results for the electronic and geometric structure of the molecule will be discussed.