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  • 02월 23일 15시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

Laboratory study of amino acid formation in the interstellar medium

2009년 2월 13일 15시 54분 58초
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목 14시 : 40분
물리화학 - Astrochemistry
저자 및
서울대학교 화학부, Korea
We present the synthesis of glycine on interstellar ice-analog films composed of water, methylamine, and carbon dioxide under irradiation of ultraviolet (UV) photons. Analysis of the UV-irradiated ice films by in situ mass spectrometric methods revealed glycine and other isomers as photochemical products. Deuterium-labeling experiments were conducted to determine the structures of the photoproducts and to examine their formation pathways. The reactions occur via photocleavages of C-H and N-H bonds in methylamine, followed by subsequent reactions of the nascent H atom with CO2, leading to the formation of HOCO, and then to glycine and carbamic acid. The photochemical synthesis of glycine occurs efficiently at the ice surfaces, and the competing photosynthesis and photodestruction processes can reach a steady-state kinetic balance at an extended UV exposure, maintaining a substantial population level of glycine. The observation suggests that amino acids can be created in the interstellar medium, and that they can also be stored in ice grains by maintaining a kinetic balance under interstellar UV irradiation. As such, the transport of amino acids in interstellar space may be possible without depleting the net abundance of amino acids in the ices but rather, increasing the structural diversity of the molecules.