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A Dedicated Effort to Investigate the Formation Chemistry of C3H2O Isomers in the ISM

Thursday, March 10, 2011

Navel Research Laboratory


Anthony J. Remijan

Assistant Scientist

ALMA Commissioning and Science Verification

National Radio Astronomy Observatory, Charlottesville, VA 22903

Tel: (434) 244-6848; Fax: (434) 296-0278





The astronomical molecular inventory currently stands at ~169 detected species and their corresponding isotopologues. Yet, given this vast molecular inventory, the formation mechanisms of even the simplest molecular species detected in these varied environments is still not well understood. Molecular isomers are also prevalent in astronomical environments and may play a role in determining the formation route of molecules in space. Molecular isomers contain the same constituent atoms yet have different structures. Recently, Lattelais et al. 2009, suggested that the isomer with the lowest zero point bonding energy (ie, the most stable isomer) should be the most abundant, and thus most easily detected in astronomical environments. We explored this theory using the C3H2O isomers. C3H2O forms three structural isomers; propadienione (CH2CCO), propynal (HCCCHO) and cyclopropenone (c-C3H2O), each with increasing bonding energy, respectively. We searched existing broadband spectral line surveys in the ISM and compared that to laboratory spectra and also simulated chemical reactions to form the C3H2O isomers using Gaussian09. All spectral explorations resulted in less then convincing proof of the presence of the two lowest energy isomers in the ISM, yet cyclopropenone is readily detected and confirmed. More observations are needed to make more solid conclusions yet the evidence is building that the lowest energy C3H2O isomers are not present in the ISM and supports the conclusion that the formation chemistry is more important than relative molecular stability in determining the abundance of molecules in astronomical environments.




Anthony J. Remijan is an Assistant Scientist in charge of ALMA Commissioning and Science Verification for the National Radio Astronomy Observatory (NRAO). He received his B.S. in Astronomy from the University of Illinois at Urbana-Champaign in 1996, his M.S. in Astronomy from Iowa State University in 1998, and a Ph.D. in Astronomy from University of Illinois at Urbana-Champaign in 2003. He was a postdoctoral research associate at NASA Goddard Space Flight Center from 2004-2006 and an ALMA postdoctoral research associate at NRAO from 2006-2008. His research interests include the discovery and study of interstellar molecules via radiotelescope observations, broadband mm-wave spectroscopy measurements and spectral analysis, and generally, the interplay between physics, astronomy, chemistry, and biology. His ambition for teaching is demonstrated by the variety of courses he has taught at the University of Maryland-University College (Introduction to Astronomy; Introduction to Physical Science; Introduction to Physical Science Laboratory), Prince George's Community College (Introduction to Astronomy), Parkland College (The Solar System; Stars, Galaxies, and the Universe; General Physics I; General Physics II; Mechanics; Electricity and Magnetism; Modern Physics), and Illinois State University (Atoms to Galaxies; Physics for Science and Engineering I; Physics for Science and Engineering II; Statics). His ambition for public outreach is demonstrated by the wide variety of public lectures he has given to promote the sciences of astrochemistry and astrobiology, speaking in venues as diverse as the Science Center at the Robert C. Byrd Green Bank Telescope facility in Green Bank, WV to the 12th Annual Coalition for National Science Funding (CNSF) Exhibition & Reception on Capitol Hill. Dr. Remijan was the recipient of the University of Illinois Excellent Teaching Award in 1998, the Iowa State University Richard G. Patrick Award for Outstanding Teaching Assistant in 1998, the Iowa State University Teaching Excellence Award in 1998, the Iowa State University Outstanding First-Year Teaching Award in 1997, and the University of Illinois Excellent Teaching Award in 1995.