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

中文翻译：

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从共振紫外拉曼光谱对煤、陆地和外星干酪根的结构和形成的新见解

摘要 共振紫外（244 nm 激发）拉曼光谱用于表征一系列煤、II 型干酪根、从原始球粒陨石中提取的不溶性有机物 (IOM) 和两个平流层行星际尘埃粒子。未成熟陆地干酪根和煤的紫外拉曼光谱与从 1 型和 2 型原始球粒陨石中提取的外星干酪根的光谱不同，可以明确识别。发现所考虑的 IDP 中耐火碳质物质的无序程度高于原始球粒陨石，证实了以前对 IDP 可见（514 nm 激发）拉曼光谱的解释。在 500-700 °C 的冷等离子体反应器中形成的球粒状有机物的实验室类似物的光谱和结构特征与天然样品的光谱和结构特征不同，挑战原太阳盘内球粒状有机物可能通过等离子体反应形成的假设。最后，紫外拉曼数据为煤在成熟过程中的结构演化提供了新的线索，并支持在镜质体反射率 Ro ~ 0.4-0.5% 时存在 sp2 结构转变。与以前的可见拉曼和红外光谱数据的比较证实了这种结构转变的存在，这与含氧物质（羧基、羟基、酮和醚基团）的急剧下降有关。因此，氧气在控制多环芳烃材料的拉曼光谱方面起着间接但重要的作用。该技术的一个潜在应用是确定地球上古代岩石中干酪根的生物起源与非生物起源，