2020ApJ...889..134Z

This laboratory work studied the production of complex organic molecules in pure methanol (CH₃OH) ices exposed to ionizing radiation in the form of energetic electrons. The chemical evolution of the ices during the electron irradiation at 10 K and subsequent warm-up phase to 300 K was monitored online and in situ via Fourier Transform Infrared spectrometry. Polyols and hydroxycarboxylic acids related absorptions were observed in the infrared spectra of the irradiated ices and residues at room temperature. The residues were analyzed via two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC x GC-TOFMS). Four polyols and five hydroxycarboxylic acids were detected. All of these compounds, except 1, 3-propanediol and 1, 3-butanediol, have been identified in the Murchison and Bell meteorites. The most abundant species, ethylene glycol, has also been found in the interstellar medium (ISM). Our findings suggest that other polyols and acids may also be present in methanol-rich star-forming regions. The non-detection of higher order sugars, such as those found in the ultraviolet photon-processed, ¹³C-methanol (¹³CH₃OH):water (H₂O):ammonia (NH₃), and ¹³CH₃OH: H₂O ice mixtures, indicates that the type of radiation source or more likely the prevalent NH₃ and/or H₂O molecules in the ISM are critical to the abiotic formation of the bio-essential sugars. Experiments are currently being designed to elucidate the roles of each component.