EPR of radicals in primitive organic matter : a tool for the search of biosignatures of the most ancient traces of life

摘要: In this paper we report on electron paramagnetic resonance (EPR) of centers in the carbonaceous matter primitive siliceous rocks, known to contain most ancient traces life. The EPR lines observed are attributed π-radicals stabilized by aromatic structure matter. It is found that line widths and shapes vary continuously during geological periods show a progressive pattern evolution from Gaussian–Lorentzian (recent) purely Lorentzian (ca. 2000 million years [Myr]), supra-Lorentzian 3500 Myr). Artificial ageing experiments allowed us define four stages maturation organic according g-factors, intensity, peak-to-peak width shape. We suggest peculiar shape for older than Myr should be related low-dimensional (two- or one-dimensional) spatial distribution spins. From these results, derive relationship between age matter, valid ages ranging about 600 Myr.