The spectroscopic characterization of the methoxy radical. III. Rotationally resolved $\skew3\tilde{A}^2A_1\text{–}\skew3\tilde{X}^2E$Ã2A1–X̃2E electronic and $\skew3\tilde{X}^2E$X̃2E submillimeter wave spectra of partially deuterated CH2DO and CHD2O radicals

Abstract

Rotationally resolved laser induced fluorescence and stimulated emission pumping Ã(2)A(1)-X̃(2)E spectra, along with pure rotational spectra in the 153-263 GHz region within the E(3/2) component of the ground state in asymmetrically deuterated methoxy radicals CH(2)DO and CHD(2)O have been observed. The combined data set allows for the direct measurement with high precision of the energy separation between the E(1/2) and E(3/2) components of the ground state and the energy separation between the parity stacks in the E(3/2) 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.