The spectroscopic characterization of the methoxy radical. III. Rotationally resolved ?~2A_1-X?~2E electronic and X~2E submillimeter wave spectra of partially deuterated CH_2DO and CHD_2O radicals

摘要

Rotationally resolved laser induced fluorescence and stimulated emission pumping A2A_1-X2E spectra, along with pure rotational spectra in the 153-263 GHz region within the E_(32) component of the ground state in asymmetrically deuterated methoxy radicals CH_2DO and CHD_2O have been observed. The combined data set allows for the direct measurement with high precision of the energy separation between the E_(12) and E_(32) components of the ground state and the energy separation between the parity stacks in the E_(32) component of the ground state. The experimentally observed frequencies in both isotopologues are fit to an effective rotational Hamiltonian accounting for rotational and spin-rotational effects arising in a near-prolate asymmetric top molecule with dynamic Jahn-Teller distortion. Isotopic dependencies for the molecular parameters have been successfully implemented to aid the analysis of these very complex spectra. The analysis of the first and second order contributions to the effective values of molecular parameters has been extended to elucidate the physical significance of resulting molecular parameters. Comparisons of measured parameters, e.g., spin-orbit coupling, rotational and spin-rotation constants, are made among the 5 methoxy isotopologues for which data is now available. Comparisons of experimental results, including the derived geometric structure at both the C_(3v) conical intersection and at the Jahn-Teller distorted minima, are made with quantum chemistry calculations.