Knowledge Bank

Laser-induced fluorescence spectroscopy of the $A~2A1\leftrightarrow X~2E$ transition of asymmetrically deuterated methoxy radicals, $CHD2O$ and C$H2DO$, has been studied. From the origin of the $A~2A1$ state to $4100cm-1$ above it, 75 fluorescence excitation bands that involve modes $\nu 2$, $\nu 3$, $\nu 5\prime$, $\nu 5\prime \prime$, $\nu 6\prime$, $\nu 6\prime \prime$ and their combinations have been observed and assigned for $CHD2O$. Harmonic frequencies, diagonal and off-diagonal anharmonicities have been determined for most of the modes of $A~2A\prime CHD2O$. A smaller set of bands has been recorded and vibrations assigned for$ CH_{2}DO$. Ten vibrational bands of $CHD2O$ and six of the $CH2DO$ are rotationally analyzed. An effective rotational Hamiltonian is proposed for the ground state, which combines the spin-orbit interaction with a special effective term that is attributable to the removal of the $X~2E$ vibronic degeneracy induced by the aymmetric deuteration. The LIF results provide a selection of intermediate states to choose from for our ongoing Stimulated Emission Pumping and fluorescence depletion spectroscopy work that is a prelude to studying the state-selective unimolecular reaction dynamics of the electronic ground state of methoxy.