Titan hosts a complex chemical engine producing a rich inventory of organic molecules in its thick atmosphere and on its surface. Some of these organics may be deposited in the liquid hydrocarbon lakes in the polar regions and form evaporite features when the lakes dry out as part of Titan’s methane/ethane cycle that is analogous to Earth’s hydrologic cycle. Modeling suggests that acetylene and butane would be the main components of such evaporite deposits. We have previously demonstrated that some organic molecules (such as benzene and ethane) readily form co-crystals in Titan-relevant conditions. We report here Raman spectroscopic evidence for a new co-crystal between acetylene and butane, which could be the most common organic co-crystal discovered so far of direct relevance to Titan’s surface. Intermolecular interactions such as those in the acetylene-butane co-crystal could modify the kinetics and equilibria of various processes (dissolution, reprecipitation, etc.) and therefore may play a key role in the formation mechanisms and timescales of landscape evolution on Titan.

中文翻译：

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乙炔和丁烷之间的共晶体：土卫六上可能普遍存在的分子矿物

泰坦拥有一个复杂的化学引擎，可以在其浓厚的大气层和其表面上产生大量的有机分子。这些有机物中的一些可能会沉积在极地地区的液态烃湖中，当这些湖变干时（这是土卫六甲烷/乙烷循环的一部分，这类似于地球的水文循环），这些蒸发物就会形成蒸发岩特征。模拟表明，乙炔和丁烷将是此类蒸发矿床的主要成分。先前我们已经证明，某些有机分子（例如苯和乙烷）在与泰坦有关的条件下很容易形成共晶体。我们在此报告拉曼光谱证据，表明乙炔和丁烷之间存在新的共晶体，这可能是迄今为止发现的与Titan表面直接相关的最常见的有机共晶体。