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Paper: Organic Carbon in Interplanetary Dust Particles
Volume: 213, Bioastronomy '99: A New Era in Bioastronomy
Page: 191
Authors: Flynn, George; Keller, L. P.; Jacobsen, C.; Wirick, S.; Miller, M. A.
Abstract: The accretion of interplanetary dust is believed to have made an important contribution of pre-biotic organic matter to the Earth [Anders, E., Nature, 342, 255-257, 1989]. Interplanetary dust particles (IDPs), about 10 microns in size, collected from the stratosphere by NASA, contain an average of 12 weight-percent carbon [Thomas, K. L. et al., GCA, 57, 1551-1566, 1993]. Although polycyclic aromatic hydrocarbons (PAHs) were found in some IDPs [Clemett, S. J., et al., Science, 262, 721-724, 1993], others are dominated by elemental carbon. We have begun a systematic study of the types and abundances of carbon in IDPs using a Scanning Transmission X-Ray Microscope (STXM) and a Fourier Transform Infrared (FTIR) microscope, both at the National Synchrotron Light Source at Brookhaven National Laboratory. All but one of the 12 IDPs examined using the STXM have have Carbon-X- ray Absorption Near-Edge Structure (C-XANES) spectra indicating the presence of significant quantities of organic carbon. The FTIR examination showed -C-H2 and -C-H3 stretching vibrations of aliphatic hydrocarbons in 4 of the 6 IDPs examined. These results indicate organic carbon, including aliphatic hydrocarbons, is common in IDPs. Taking a 2 weight-percent organic content, modeling indicates the accretion of IDPs currently contributes more than 10,000 kilograms/year of unpyrolyzed (not heated above 600^ˆC) organic matter to Earth.
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