UV Photolysis of Glycine on Ice Films: Implication for Photosynthesis and Photodestruction of Amino Acids in Interstellar Medium

摘要

Extraterrestrial amino acids and their possible formation and destruction processes are an intriguing research topic in astrochemistry and astrobiology. We studied the ultraviolet (UV) photolysis of glycine under conditions similar to that of the interstellar medium by irradiating UV light onto an ice film adsorbed with glycine at low temperature (<60 K). UV light photodissociated glycine into smaller molecules, such as ammonia, methylamine, CH2NH2, and CO2H. Protonated ions of the neutral species, including NH4+, CH3NH3+, and possibly HC(OH)(2)(+), were also detected. The observed photofragments support the possibility that interstellar amino acids undergo competing photosynthesis and photodestruction processes on ice grains under UV irradiation, and a feedback mechanism between these two processes may assist the storage and transport of amino acids in interstellar space.