Publications

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1996
Becker, L, Poreda RJ, Bada JL.  1996.  Extraterrestrial helium trapped in fullerenes in the sudbury impact structure. Science. 272:249-252.   10.1126/science.272.5259.249   AbstractWebsite

Fullerenes (C-60 and C-70) in the Sudbury impact structure contain trapped helium with a He-3/He-4 ratio of 5.5 x 10(-4) to 5.9 x 10(-4). The He-3/He-4 ratio exceeds the accepted solar wind value by 20 to 30 percent and is higher by an order of magnitude than the maximum reported mantle value, Terrestrial nuclear reactions or cosmic-ray bombardment are not sufficient to generate such a high ratio. The He-3/He-4 ratios in the Sudbury fullerenes are similar to those found in meteorites and in some interplanetary dust particles. The implication is that the helium within the C-60 molecules at Sudbury is of extraterrestrial origin.

1994
Becker, L, Bada JL, Winans RE, Hunt JE, Bunch TE, French BM.  1994.  Fullerenes in the 1.85-Billion-Year-Old Sudbury Impact Structure. Science. 265:642-645.   10.1126/science.11536660   AbstractWebsite

Fullerenes (C-60 and C-70) have been identified by laser desorption, laser desorption postionization, and high-resolution electron-impact mass spectrometry in shock-produced breccias (Onaping Formation) of the Sudbury impact structure in Ontario, Canada, The C-60 isotope is present at a level of a few parts per million. The fullerenes were likely synthesized within the impact plume from the carbon contained in the bolide. The oxidation of the fullerenes during the 1.85 billion years of exposure was apparently prevented by the presence of sulfur in the form of sulfide-silicate complexes associated with the fullerenes.

1992
Zenobi, R, Philippoz JM, Zare RN, Wing MR, Bada JL, Marti K.  1992.  Organic-Compounds in the Forest Vale, H4 Ordinary Chondrite. Geochimica Et Cosmochimica Acta. 56:2899-2905.   10.1016/0016-7037(92)90366-q   AbstractWebsite

We have analyzed the H4 ordinary chondrite Forest Vale for polycyclic aromatic hydrocarbons (PAHs) using two-step laser mass spectrometry (L2MS) and for amino acids using a standard chromatographic method. Indigenous PAHs were identified in the matrices of freshly cleaved interior faces but could not be detected in pulverized silicates and chondrules. No depth dependence of the PAHs was found in a chipped interior piece. Amino acids, taken from the entire sample, consisted of protein amino acids that were nonracemic, indicating that they are terrestrial contaminants. The presence of indigenous PAHs and absence of indigenous amino acids provides support for the contention that different processes and environments contributed to the synthesis of the organic matter in the solar system.