Search of Natural Fullerenes in Chinese Coal Layers

关于自然界中是否存在富勒烯的争论仍未解决。据称在KT和PT等黑色地质层或从陨石撞击坑收集的含碳岩石中检测到的C_<60>的浓度水平通常小于0.1 ppm，难以证实。唯一报道天然富勒烯浓度足够高的案例是中国云南一平郎煤矿的煤样。不幸的是，关于这个罕见样本的信息是罕见的和不准确的。搜索的目的是通过我们自己的调查来证实报告。与地质学家进行了三次考察，不仅到一平浪煤矿，还到中国其他煤矿亲自采集煤样。最后一次旅行是在南非，在那里发现了岩浆侵入的新型煤层和世界上最古老、最大的陨石坑。结果如下：(1)仅一平郎煤样中C_<60>的含量被证实，C_<60>/C_<70>的含量高达0.3%。这种特殊的煤样除了含有富勒烯外，还含有烟灰状微观结构的纳米级石墨纳米颗粒，以及两种新矿物，可能是已知矿物的高温高压改性物。(2)收集的所有其他样品的富勒烯分析均为阴性。尽管有这样的结果，出于安全考虑，我们没有被允许进入地下矿井，也没有研究三维地下图。然而，经过耐心和长期的谈判，我们最终成功地从一平郎煤矿获得了大量的煤炭样本，并记录了准确的地下位置。飞行时间质谱仪的初步测试证明其中一些样本呈阳性，目前正在进行高效液相色谱法的定量分析。根据一些证据，我们提出自然冲击压缩是煤中C_<60>形成的原因。在激波管实验中，有强有力的证据证明C60/C70的形成。我们正在与美国国家航空航天实验室合作研究在加热风洞中等离子体喷射流照射石墨表面时富勒烯的形成。少

Debates on the existence of fullerenes in nature still remain unsettled. Concentration levels of C_<60> allegedly detected in black geological layers like KT and PT or from carbon-containing rocks collected from meteorite impact craters are generally less than 0.1 ppm and are difficult to confirm. The only case that reports sufficiently high natural fullerene concentrations is a coal sample taken from Yipinglang coal mine in Yunnan, China. Unfortunately the information on this rare sample was rare and inaccurate. The purpose of this search is to confirm the report by our own survey.Three survey trips were made with geologists to not only the Yipinglang mine but also to the other coal mines in China to collect coal samples ourselves. A final trip was made to South Africa where novel coal beds intruded by magmas and the world's oldest and largest meteorite crater were surveyed.The results are as follows. (1) Only the Yipinglang coal sample that had been reported to contain C_<60> was con … More firmed to contain as high as 0.3 % of C_<60>/C_<70>. This particular coal sample was found to contain, in addition to fullerenes, soot-like microstructure of nano-sized graphitic nanoparticles, and two kinds of new minerals, probably a high temprature-high pressure modifications of known minerals. (2) All other samples collected were negative with respect to the fullerene analysis.In spite of these results, we were not allowed to enter the underground mine for the reason of safety, neither to study 3D underground maps. However, after patient and long negotiations, we eventually succeeded in obtaining large number of coal samples from Yipinglang mine whose exact underground locations were recorded. Preliminary tests on a time-of-flight mass spectrometer proved positive for a few samples among them and currently work is going on for quantitative analysis with a HPLC.Based on several pieces of evidence, we propose natural shock compression as the cause of formation of C_<60> in coal. Strong evidence is available for the verification of the formation of C60/C70 in a shock tube experiment. We are in the process of cooperative research with National Aerospace Laboratory to study the formation of fullerenes upon irradiation of plasma jet stream onto graphite surface in a heated wind tunnel. Less