Laboratory Measurement of Millimeter-wave Transitions of 13 CH 2 DOH for Astronomical Use

• Published in: The Astrophysical journal 2022-06, Vol.932 (2), p.101
• Main Authors: Ohno, Yuki, Oyama, Takahiro, Tamanai, Akemi, Zeng, Shaoshan, Watanabe, Yoshimasa, Nakatani, Riouhei, Sakai, Takeshi, Sakai, Nami
• Format: Article
• Language: English
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ac6b9e

Methanol (CH 3 OH) is an abundant interstellar species and is known to be an important precursor of various interstellar complex organic molecules. Among the methanol isotopologues, CH 2 DOH is one of the most abundant isotopologues and it is often used to study the deuterium fractionation of CH 3 OH in interstellar medium. However, the emission lines of CH 2 DOH can sometimes be optically thick, making the derivation of its abundance unreliable. Therefore, observations of its presumably optically thin 13 C substituted species, 13 CH 2 DOH, are essential to overcome this issue. In this study, the rotational transitions of 13 CH 2 DOH have been measured in the millimeter-wave region from 216 GHz to 264 GHz with an emission-type millimeter- and submillimeter-wave spectrometer by using a deuterium and 13 C enriched sample. The frequency accuracy of measured 13 CH 2 DOH is less than a few kHz, and the relative line intensity error is less than 10% in most of the frequency range by taking advantage of the wide simultaneous frequency-coverage of the emission-type spectrometer. These results offer a good opportunity to detect 13 CH 2 DOH in space, which will allow us to study the deuterium fractionation of CH 3 OH in various sources through accurate determination of the CH 2 DOH abundance.