XANES analysis of organic residues produced from the UV irradiation of astrophysical ice analogs |
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Authors: | M Nuevo SN Milam SA Sandford BT De Gregorio GD Cody ALD Kilcoyne |
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Institution: | 1. NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035, USA;2. SETI Institute, 189 N. Bernardo Ave., Suite 100, Mountain View, CA 94043, USA;3. Naval Research Laboratory, Code 6366, 4555 Overlook Ave. SW, Washington, DC 20375, USA;4. Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC 20015, USA;5. Advanced Light Source, Lawrence Berkeley National Laboratory, 6 Cyclotron Rd., Berkeley, CA 94720, USA |
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Abstract: | Organic residues formed in the laboratory from the ultraviolet (UV) photo-irradiation or ion bombardment of astrophysical ice analogs have been extensively studied for the last 15 years with a broad suite of techniques, including infrared (IR) and UV spectroscopies, as well as mass spectrometry. Analyses of these materials show that they consist of complex mixtures of organic compounds stable at room temperature, mostly soluble, that have not been fully characterized. However, the hydrolysis products of these residues have been partly identified using chromatography techniques, which indicate that they contain molecular precursors of prebiotic interest such as amino acids, nitrile-bearing compounds, and amphiphilic compounds. In this study, we present the first X-ray absorption near-edge structure (XANES) spectroscopy measurements of three organic residues made from the UV irradiation of ices having different starting compositions. XANES spectra confirm the presence of different chemical functions in these residues, and indicate that they are rich in nitrogen- and oxygen-bearing species. These data can be compared with XANES measurements of extraterrestrial materials. Finally, this study also shows how soft X rays can alter the chemical composition of samples. |
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Keywords: | Ices UV irradiation XANES spectroscopy Extraterrestrial materials |
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