MILLIMETRE-WAVE SPECTRUM OF ISOTOPOLOGUES OF ETHANOL FOR RADIO ASTRONOMY

Complex molecules have been identified in star-forming regions and their formation is linked to the specific physical and chemical conditions there. They are suspected to form a role in the origins of life. Amongst these, ethanol is a fairly abundant molecule in warmer regions. For this reason, we have recently carried out laboratory measurements and analyses of the rotational spectra of the three mono-substituted deuterium isotopologues of ethanol (one of which, chem{CH_2DCH_2OH}, exists as two distinct conformers according to the position of the deuterium atom with respect to the molecular skeleton). Measurements were taken between 35-500 GHz, allowing accurate predictions in the range of radio telescopes. We have concentrated on the lowest energy textit{anti} conformers. The dataset was constrained for fitting with a standard Watson-S reduction Hamiltonian by rejecting transitions from high-lying states, which appear to be perturbed by the gauche states, and by averaging some small methyl torsional splits. This treatment is compatible with the needs for a first search in the interstellar medium, in particular in spectra taken by ALMA. For this purpose an appropriate set of predictions will be included on the Cologne Database for Molecular Spectroscopy. Previous results on the two mono-substituted chem{^{13}C} isotopologuesfootnote{Bouchez et al, JQSRT 113 (11), pp. 1148-1154, 2012.} which led to a tentative detection in Sgr B2(N)footnote{Belloche et al. A&A 559, id.A47, 187pp., 2013.} will be briefly summarized and compared with the latest measurements. The usefulness of studying different isotopologues in the interstellar medium will also be rapidly addressed