Unprecedented Molecular Diversity Revealed in Meteoritic Insoluble Organic Matter: The Paris Meteorite's Case

Abstract : The insoluble organic matter (IOM) contained in carbonaceous chondrites has witnessed a diverse suite of processes possibly starting from the evolution of the parent molecular cloud down to the protosolar nebula and finally to asteroidal processes that occurred on the chondrites' parent bodies. Laser desorption coupled with ultra-high-resolution mass spectrometry reveals that the IOM of the Paris meteorite releases a large diversity of molecules. Various molecular families ranging from hydrogenated amorphous carbon to CHNOS aromatic molecules were detected with heteroatoms (nitrogen, oxygen, and sulfur) mainly incorporated within aromatic structures. Molecules bearing nitrogen atoms present a significant variation in aromaticity. These unprecedented results allow the proposal that small molecules bearing heteroatoms could be trapped in the large macromolecular network of the IOM by hydrophobic interactions. This molecular diversity could originate from different sources, such as the soluble organic matter, the hydrothermal alteration inside the Paris's parent body, or even generated during the IOM extraction procedure. It has to be noted that some of the molecular diversity may reflect fragmentation and rearrangement of the IOM constituents during the laser desorption ionization, although care was taken to minimize such damage.