New insights into the structure and formation of coals, terrestrial and extraterrestrial kerogens from resonant UV Raman spectroscopy

摘要: Abstract Resonant UV (244 nm-excitation) Raman spectroscopy was used to characterize a series of coals, type II kerogens, Insoluble Organic Matter (IOM) extracted from primitive chondrites and two stratospheric Interplanetary Dust Particles. UV-Raman spectra immature terrestrial kerogens coals are distinct those extraterrestrial 1 2 chondrites, allowing unambiguous identification. The degree disorder in the refractory carbonaceous matter considered IDPs is found be higher than confirming former interpretation visible (514 nm-excitation) IDPs. Spectral structural features laboratory analogues chondritic organic formed cold plasma reactors at 500–700 °C differ natural samples, challenging hypothesis that within protosolar disk may form through reactions. Finally, data shed new light evolution during maturation support presence an sp2 transition vitrinite reflectance Ro ∼ 0.4–0.5%. Comparison with infrared spectroscopic confirms existence this transition, which related dramatic drop oxygenated species (carboxyl, hydroxyl, ketone ether groups). Oxygen thus plays indirect but significant role control polyaromatic materials. A potential application technique determination biotic versus abiotic origin ancient rocks on Earth, soils Mars otherwise difficult classical visible-excitation spectroscopy.