Millimeter- and submillimeter-wave spectroscopy of thioformamide and interstellar search toward Sgr B2(N)

Abstract

Thioformamide NH2CHS is a sulfur-bearing analog of formamide NH2CHO. The latter was detected in the interstellar medium back in the 1970s. Most of the sulfur-containing molecules detected in the interstellar medium are analogs of corresponding oxygen-containing compounds. Therefore, thioformamide is an interesting candidate for a search in the interstellar medium. The rotational spectrum of thioformamide was measured and analyzed in the frequency range 150 to 660 GHz using the Lille spectrometer. We searched for thioformamide toward the high-mass star-forming region Sagittarius (Sgr) B2(N) using the ReMoCA spectral line survey carried out with the Atacama Large Millimeter/submillimeter Array (ALMA). Accurate rotational constants were obtained from the analysis of the ground state of parent, 34S, 13C, and 15N singly substituted isotopic species of thioformamide. For the parent isotopolog, the lowest two excited vibrational states, v12 = 1 and v9 = 1, were analyzed using a model that takes Coriolis coupling into account. Thioformamide was not detected toward the hot cores Sgr B2(N1S) and Sgr B2(N2). The sensitive upper limits indicate that thioformamide is nearly three orders of magnitude at least less abundant than formamide. This is markedly different from methanethiol, which is only about two orders of magnitude less abundant than methanol in both sources. The different behavior shown by methanethiol versus thioformamide may be caused by the preferential formation of the latter (on grains) at late times and low temperatures, when CS abundances are depressed. This reduces the thioformamide-to-formamide ratio, because the HCS radical is not as readily available under these conditions.

References in corpus (7)

• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• Detection of a branched alkyl molecule in the interstellar medium: iso-propyl cyanide
• Formation of Complex Organic Molecules in Cold Interstellar Environments through non-diffusive grain-surface and ice-mantle chemistry
• New molecules in IRC+10216: confirmation of C${}_5$S and tentative identification of MgCCH, NCCP, and SiH${}_3$CN
• Formation of Glycerol through Hydrogenation of CO ice under Prestellar Core Conditions
• First detection of interstellar S2H
• Far-infrared laboratory spectroscopy of aminoacetonitrile and first interstellar detection of its vibrationally excited transitions

Cited by in corpus (10)

• Thiols in the ISM: first detection of HC(O)SH and confirmation of C${}_2$H${}_5$SH
• Far-infrared laboratory spectroscopy of aminoacetonitrile and first interstellar detection of its vibrationally excited transitions
• Resolving desorption of complex organic molecules in a hot core: Transition from non-thermal to thermal desorption or two-step thermal desorption?
• Toward the limits of complexity of interstellar chemistry: Rotational spectroscopy and astronomical search for n- and i-butanal
• Toward a global model of the interactions in low-lying states of methyl cyanide: rotational and rovibrational spectroscopy of the $v_4=1$ state and tentative interstellar detection of the $v_4=v_8=1$ state in Sgr B2(N)
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• Design and Implementation of a New Apparatus for Astrochemistry: Kinetic Measurements of the CH + OCS Reaction and Frequency Comb Spectroscopy in a Cold Uniform Supersonic Flow
• Rotation-tunneling spectrum and astrochemical modeling of dimethylamine, CH${}_3$NHCH${}_3$, and searches for it in space
• The salty emission of the intermediate-mass AGB star OH 30.1 -0.7
• Global flow regimes of hot Jupiters