Organic compounds of th Pueblito de Allende meteorite

Abstract

The CV3 Pueblito de Allende meteorite is used to test new in situ methods to identify organic compounds. These methods can potentially be a good alternative to avoid the difficult extraction methods, reducing the risk of losing organic molecules and contaminating the samples with terrestrial organics. The distribution, formation, and characteristics of the organic compounds of the Pueblito de Allende meteorite are studied by Electron MicroProbe (EMP), Raman spectroscopy and Surface Enhanced Raman Spectroscopy (SERS) and nuclear magnetic resonance (NMR). Elemental maps, spot analysis and Raman measurements show the heterogeneous distribution of organic compounds in the matrix and chondrules. The G- and D-bands are used to reveal the differences between the thermally stressed organics of Allende and the relative unaltered organics of other CV3 chondrites. The SERS method, where synthesized silver nanoparticles are added to the surface of minerals have an enhancement effect (~106) on organics, is used to show that this method works when the organics are added to the minerals in thin film. This study shows that the enhancements effects on the intensities of the organics are dramatically reduced when the silver colloids are used to determine the organic compounds imbedded in the matrix. The G- and D-band are enhanced slightly (101-102), but no other organic compounds could be detected. The addition of chloride ions used to stabilize the silver particles decreases the enhancements effects even more.