Far infrared laser, high resolution submillimeter wave, far infrared, and infrared, spectroscopy of molecule of astrophysical significance: deuterated methanol species [formula omitted

Abstract

In this report, a wide range of spectroscopic studies was undertaken on the astrophysical significant deuterated methanol (CD3OD) species. In the submillimeter wave(SMMW) wave a large number of very accurate spectral line positions in the useful range of 130-750GHz have been reported. The actual spectral recording of the spectrum in the range 325-344GHz with a high signal to noise ratio (S/N) have been presented. These will serve the radio astronomers a laboratory back-up to detect this species in interstellar space which will help to determine the deuterium/Hydrogen (D/H) ratio to understand the evolution of chemistry and the formation process of large molecules in space. At the low temperature of interstellar space, the quantum tunneling effect can be better understood by the deuterium fragmentation process. The study is extended in the far-infrared (FIR) region by high-resolution Fourier transform measurements. The spectral lines originating in the first excited state and those terminating in the first excited states have been assigned. About 2500 lines have been identified and atlas of the assigned lines along with previously not repotted, lines have been reported. The Hamiltonian model used has been clearly explained in terms of rotation and torsional-rotational molecular motion. All the SMMW(accuracy±100kHz) lines along with the FIR lines (accuracy ±0.0004cm-1) have been fitted with the model and the parameters determined. The molecular parameters reproduce the measured transition wavenumbers approximately within the experimental uncertainty. It should be noted the exact term values for the connected ground state levels are included in an Appendix-1, for economy this is submitted as a depository. In the infrared (IR) region a number of vibrational bands have been recorded but the presence of water vapour hindered the analysis work. However, with the knowledge of the molecular parameters and low-resolution knowledge about 10 different CO2 lasers pumped FIR laser system have been assigned and a number of FIR lines have been predicted.