Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of the low-molecular-weight, solvent extractable compounds and the insoluble organic macromolecular material.  Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains.  Here we report on new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons.  We have applied the highly sensitive experimental techniques of gas chromatography-mass spectrometry and atmospheric-pressure photoionization Fourier transform mass spectrometry for molecular characterization of this residue.  The profile of low-molecular-weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. All of these results are consistent with the possibility that the solid-phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.  Applications of our results can be envisioned for Titan and for interstellar chemistry as well.

Irradiated benzene ice provides clues to meteoritic organic chemistry

246th National Meeting (2013)

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