Far infrared laser, millimeter-wave and microwave Microwave stark, millimeter wave, far infrared, infrared and far infrared laser spectroscopy of methanol-OD ([formula omitted]): Precise dipole moment and millimeter-wave atlas of astrophysical significance

Abstract

In this report accurate microwave (MW) Stark effect measurements have been performed to obtain precise dipole moment and precise zero-field microwave frequencies of singly deuterated quasi symmetric CH3OD methanol species. This species is of significance to radio astronomers to study the hydrogen-deuterium exchange in interstellar space in cold clouds to study basic chemical processes in other worlds. The telescope facilities at Atacama Large millimeter Array (ALMA), the facilities at Institute for Radio Astronomy in the Millimeter Range (IRAM), and the NASA's floating Stratospheric Observatory for Infrared Astronomy (SOFIA), etc. routinely gauge the sky in the millimeter-wave (MMW) to infrared spectral (IR) regions (Drozdovskaya et al., 2019; Faure et al., 2015; Neill et al., 2013; Peng et al., 2012; Taquet et al., 2011; Whittet et al., 2011; Parise et al., 2004, 2002, 2002, 2002, 2003, 2003, 2003; Johns et al., 1998; Charnley et al., 1997). The laboratory back up of the millimeter region of CH3OD is of importance to astronomers for such studies as the determination of column densities and the deuteration process. In the present study, the MMW spectra previously recorded with unprecedented accuracy (Mukhopadhyay and Bo Duan, 2000; Mukhopadhyay et al., 1997; Wang et al., 2001; Mukhopadhyay, 1999; Mukhopadhyay and Bo Duan, 2000; Walsh et al., 2000) are presented at atlas form with minute details to aid such detection. The dipole results also should aid to find the strength of individual lines. In the IR region, the off-axis deuteration pushes the of the absorption bands of the molecule to the lower region, particularly the increased asymmetry of the molecule spreads the COD- bending and CO stretching bands in a wide frequency range making them more accessible to strong CO2 lasers resulting in preferential population transfer to excited states of the molecule. Thus making this species a prolific source of coherent laser emission radiation in the scarce FIR region (Landsberg, 1980; Gastaud et al., 1980; Kon et al., 1984; Pereira et al., 1994; Telles et al., 1999; Lundsgaard et al., 1968; Dijkerman and Ruitenberg, 1969; Amano, 1981; Lees et al., 2013; Petersen, 2020). In this work, a large number of CO2 laser pump/FIR laser systems have been identified with specific quantum numbers and predict many new lines. Schematic diagrams have been presented for the emission and prediction process along with important experimental diagnostic information about relative polarization. The assignments will aid the optimization of laser output and the predictions will enable new coherent light sources in the FIR region.