Synthesis of amino acid precursors from simulated interstellar media by high‐energy particles or photons

SUMMARY Extraterrestrial organic compounds have been considered as important sources for the origin of life on the Earth. In order to study the formation of organic compounds found in extraterrestrial bodies, simulated interstellar media were irradiated with high-energy particles or photons. Particles used were protons from a Van de Graaff accelerator, protons and helium ions from a cyclotron, electrons from a synchrotron, and heavy ions from the “HIMAC” heavy ion accelerator. Photons used were UV light and soft X-rays from a synchrotron. Gamma-ray irradiation was performed by using a 60 Co source. Amino acid precursors were formed from a mixture of carbon monoxide (or methodanol), ammonia (or nitrogen), and water by high-energy particles, gamma rays, or X-rays. If nitrogen molecule was used as N-source, amino acid precursors could be formed by high-energy particles, X-rays and gamma rays, but not by UV light. When ammonia was used, amino acid precursors were detected in all cases, but energy yields (G-values) of amino acid precursors by high-energy particles were much higher than those by UV or X-rays photons. Possible formation of amino acid precursors in interstellar environments was discussed from the point of view of chemical evolution toward origins of life. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(3): 15–21, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/ecj.10069