High resolution spectroscopy of CH 3OD involving the ground and first excited torsional states in the vibrational ground state

Abstract

In this work, the reduced eighth order Hamiltonian parameters of CH 3OD have been determined using the high resolution Fourier transform far-infrared (FIR) assigned transitions in the ground and first excited torsional states. The data set consisted of 2348 FIR transitions with the rotational angular momentum J<21 and K<7. In order to achieve stability of the fit 275 microwave (MW) and millimetre-wave (MMW) transitions have also been included in the data set. This has been fitted with a recently developed eighth order effective Hamiltonian model to derive the molecular parameters. The results indicate that the model developed for the parent methanol species is valid for the methanol-OD species as well. The fit converged with an overall deviation of 0.0008 cm −1, which is of the same order of magnitude as the uncertainty of the Fourier transformed peaks. The results will allow the energy levels of the molecule to be calculated with much more improved precision which will be useful for the discovery of new FIR laser emission and the discovery of this molecular species in interstellar space.