Millimeter- and submillimeter-wave spectrum of trans-formaldoxime (CH2NOH)

Luyao Zou,Laurent Margulès,Jean-Claude Guillemin,Roman A Motiyenko

doi:10.1051/0004-6361/202040142

Abstract

Context. Among the six atoms of N-containing molecules with the formula of CH3NO, only formamide (H2NCHO), the most stable structural isomer, has been detected in the interstellar medium (ISM). The formaldoxime isomer may be formed, for example, by the reaction of formaldehyde (H2CO) or methanimine (H2CNH) and hydroxylamine (H2NOH), which are all detected in the ISM. The lack of high accuracy millimeter- and submillimeter-wave measurements hinders the astronomical search for formaldoxime. Aims. The aim of this work is to provide the direct laboratory measurement of the millimeter- and submillimeter-wave spectrum of trans-formaldoxime. Methods. Formaldoxime was synthesized and its rotational spectrum was recorded at room temperature in a glass flow cell using the millimeter- and submillimeter-wave spectrometer in Lille. The SPFIT program in the CALPGM suite was used to fit the spectrum. Results. Rotational lines of trans-formaldoxime from both the ground state and v12 = 1 vibrational excited states have been measured and assigned from 150 to 660 GHz. Spectroscopic constants were derived to the tenth order using both Watson’s A and S reduction Hamiltonian.

Highlights

Of the little more than 200 molecules detected in the interstellar medium (ISM) (McGuire 2018), about 20 compounds with six atoms constitute the series of the smallest complex organic molecules (COMs) (Herbst & van Dishoeck 2009)
Spectroscopic constants were derived to the tenth order using both Watson’s A and S reduction
Of the little more than 200 molecules detected in the interstellar medium (ISM) (McGuire 2018), about 20 compounds with six atoms constitute the series of the smallest complex organic molecules (COMs) (Herbst & van Dishoeck 2009)

Summary

Introduction

Of the little more than 200 molecules detected in the interstellar medium (ISM) (McGuire 2018), about 20 compounds with six atoms constitute the series of the smallest complex organic molecules (COMs) (Herbst & van Dishoeck 2009). This is the most abundant group among COMs, an observation consistent with the fact that the number of molecules detected decreases with the number of atoms. To find new compounds in the ISM, the choice of new candidates is mainly based on the analogy with the molecules detected, the possible chemistry of each interstellar cloud, and the physical parameters such as the relative thermodynamic stability of the isomers. The following isomers in relative thermodynamic stability are the tautomer C-hydroxymethanimine (methanimidic acid, HN=CHOH), which is 13.4 kcal mol−1 less stable than formamide, and formaldoxime (CH2 NOH), which is

Methods

Results

Conclusion