2023MNRAS.524.1211M

The main isotopologue of 2-hydroxyacetonitrile (glycolonitrile; HOCH₂CN) has recently been detected in the interstellar medium (ISM). To date, no rotational spectroscopy of 2-hydroxyacetonitrile ¹³C-isotopologues studies has been carried out and only few centimetre-wave measurements of one deuterated isotopologue (DOCH₂CN) exist. The rotational spectrum of the 2-hydroxyacetonitrile ¹³C-isotopologues and DOCH₂CN was investigated from 150 to 530 GHz. As the parent isotopic species, the other 2-hydroxyacetonitrile isotopologues exhibit large amplitude motion due to the torsion of the hydroxyl group. The analyses of the spectra were carried out using the reduced axis system (RAS) formalism and Watson's S-reduction Hamiltonian implemented in the SPFIT code. More than 3000 lines were fitted for the three studied isotopologues, with quantum number values reaching 60-67 for J and 21-25 for K_a depending on the species. Accurate line lists up to 600 GHz and partition functions are provided. A search for these isotopologues in SMM1-a and IRAS 16293 B surveys resulted in non-detections; upper limits to the column density were determined. The accurate spectroscopic prediction of their spectra provided in this work will allow astronomers to continue the search for 2-hydroxyacetonitrile isotopologues in the ISM.