Hydrogen cyanide production due to mid-size impacts in a redox-neutral N2-rich atsmophere
Hydrogen cyanide production due to mid-size impacts in a redox-neutral N2-rich atsmophere
复制标题
氧化还原中性、富含 N2 的大气中由于中等规模的撞击而产生氰化氢
DOI：
10.1007/s11084-013-9339-0
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发表时间：
2013
影响因子：
2
通讯作者：
T. Matsui
中科院分区：
文献类型：
--
作者：
Kurosawa;K.;S. Sugita;K. Ishibashi;S. Hasegawa;Y. Sekine;N. O. Ogawa;T. Kadono;S. Ohno;N. Ohkouchi;Y. Nagaoka;T. Matsui
氰化物是生命起源最重要的分子之一。在这里，我们展示了中等大小（直径 0.1-1 公里）的陨石的重要性，因此频繁的陨石撞击对早期地球上的氰化物库存有影响。通过撞击和激光实验研究了倾斜撞击后随后的空气动力烧蚀和与周围大气的化学反应。聚碳酸酯弹丸和石墨被用作陨石有机物的实验室类似物。对撞击产生的烧蚀蒸气的光谱观察表明，激光照射富氮气体中的石墨可以产生类似于倾斜撞击产生的热力学环境。因此，激光烧蚀被用来研究空气动力学过程后的最终化学产品。我们发现，即使环境气体含有高达几百毫巴的二氧化碳，汽化碳的很大一部分 (>0.1 mol%) 也会转化为 HCN 和氰化物冷凝物。因此，在早期地球条件下，直径为 600 m 的富碳陨石撞击后，氰化物的柱密度将在约 102 平方公里的范围内达到约 10 mol/m2。这种在时间和空间上集中的氰化物供应可能在生命起源中发挥了重要作用。
Cyanide compounds are amongst the most important molecules of the origin of life. Here, we demonstrate the importance of mid-size (0.1–1 km in diameter) hence frequent meteoritic impacts to the cyanide inventory on the early Earth. Subsequent aerodynamic ablation and chemical reactions with the ambient atmosphere after oblique impacts were investigated by both impact and laser experiments. A polycarbonate projectile and graphite were used as laboratory analogs of meteoritic organic matter. Spectroscopic observations of impact-generated ablation vapors show that laser irradiation to graphite within an N2-rich gas can produce a thermodynamic environment similar to that produced by oblique impacts. Thus, laser ablation was used to investigate the final chemical products after this aerodynamic process. We found that a significant fraction (>0.1 mol%) of the vaporized carbon is converted to HCN and cyanide condensates, even when the ambient gas contains as much as a few hundred mbar of CO2. As such, the column density of cyanides after carbon-rich meteoritic impacts with diameters of 600 m would reach ~10 mol/m2over ~102km2under early Earth conditions. Such a temporally and spatially concentrated supply of cyanides may have played an important role in the origin of life.