Torsional energies, matrix elements and predictions of microwave transitions in CH2DOD

Abstract

In this study the torsional–rotational molecular parameters of asymmetrically deuterated methanol (CH2DOD) have been calculated up to K=15 in the torsional vibrational ground state. Matrix elements for ΔK=±1 transitions have been calculated up to the fourth excited torsional state. Using previously observed microwave (MW) transitions effective state dependent molecular parameters have been evaluated for the states involved. These parameters allow the predictions for unobserved microwave transitions to be made with a precision which should enable future laboratory and astrophysical detection. The matrix elements and the torsional energies will be valuable in the assignments of far-infrared absorption spectra and optically pumped far-infrared laser lines in this molecular isotopomer of methanol. The energy levels calculated will form a useful data-base to aid in the detection of this isotopic variant of methanol in astrophysical sources which might be of useful for the determination of parameters like the D/H ratio in the universe.