对印度拉贾斯坦邦穆库恩普拉陨石最新样本的高分辨率显微镜和拉曼光谱研究：存在纳米钻石
High Resolution Microscopy and Raman Spectroscopic Studies on the Freshest Mukundpura Meteorite, Rajasthan, India: Presence of Nanodiamond
AI总结：
研究发现印度陨石中存在纳米钻石，通过高分辨率显微镜和拉曼光谱分析证实其存在，并探讨其与地质事件的关系。
摘要：
碳质球粒陨石在恒星演化以及地球生命演化中具有特殊意义。2017年6月6日在印度拉贾斯坦邦杰伊普尔市穆库恩普拉村坠落的碳质陨石是一种罕见的CM2（碳质球粒陨石）。我们对典型薄片进行了高分辨率扫描和透射电子显微镜（TEM）研究，显示出丰富的铱（Ir）、五倍体石（NiS）和更有趣的是结晶碳（C）颗粒。这些结晶碳颗粒在最新穆库恩普拉陨石中呈现出类似纳米钻石的特征。对结晶碳颗粒进行了高分辨率拉曼光谱测量，显示出三个清晰的峰，其中在1315 cm⁻¹处有振动模式，1150 cm⁻¹处出现弱振动模式，证实了穆库恩普拉陨石中存在纳米晶体钻石。中心在1360 cm⁻¹和1575 cm⁻¹（平均值）的宽峰表明存在石墨碳，同时存在明显的纳米晶体钻石。纳米晶体钻石的平均尺寸约为3-5 nm。该陨石中高铱含量支持了与陨石撞击相关的地质层界线（如白垩纪-古近纪界线）中铱异常现象，该现象导致了生物灭绝。
英文摘要：
Carbonaceous Chondrites have special significance in the stellar evolution and in particular in the evolution of life on earth. The carbonaceous meteorite that fell in Mukundpura village, Jaipur, Rajasthan on 6th June 2017 is one such rare CM2 (Carbonaceous Chondrite) carbonaceous meteorite. We carried out high resolution scanning and transmission electron microscopic (TEM) studies on typical thin sections, showing abundant grains of iridium (Ir), pentlandite (NiS), and more interestingly crystalline carbon (C). These crystallite carbon grains resemble nanodiamond like signature in the freshest Mukundpura meteorite. The high-resolution Raman spectroscopic measurements are carried out on the crystalline carbon grains, showing well resolved three distinct peaks with a vibrational mode at 1315 cm-1, with the onset of a weak vibrational mode at 1150 cm^-1, substantiating the observation of nanocrystalline diamond in Mukundpura meteorite. The broad peak centered at 1360 cm^-1 and 1575 cm^-1 (as an average), suggest the presence of graphitic carbon as well together with apparent presence of nanocrystalline diamond. The average size of nanocrystalline diamond is ~ 3-5 nm. High iridium content in this meteorite supports the meteoric impact related iridium anomaly in geological stratigraphic boundaries (e.g.Cretaceous-Tertiary boundary) that has caused mass extinction of flora and fauna.
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