Formation mechanism of glycolaldehyde and ethylene glycol in astrophysical ices from HCO• and •CH2OH recombination: An experimental study

Abstract

Among all existing complex organic molecules, glycolaldehyde HOCH2CHO and ethylene glycol HOCH2CH2OHare two of the largest detected molecules in the interstellar medium. We investigate both experimentally and theoretically the low-temperature reaction pathways leading to glycolaldehyde and ethylene glycol in interstellar grains. Using infrared spectroscopy, mass spectroscopy and quantum calculations, we investigate formation pathways of glycolaldehyde and ethylene glycol based on HCO• and •CH2OH radical-radical recombinations. We also show that •CH2OH is the main intermediate radical species in the H2CO to CH3OH hydrogenation processes. We then discuss astrophysical implications of the chemical pathway we propose on the observed gas-phase ethylene glycol and glycolaldehyde.