标题： 吡啶：乙炔共晶的实验表征及其对泰坦星表面的意义 显示英文标题

标题： Experimental Characterization of the Pyridine:Acetylene Co-crystal and Implications for Titan's Surface

摘要： 土卫六是土星最大的卫星，其大气和表面存在大量的有机化合物，这些化合物相互作用。诸如共晶体之类的低温矿物可能会影响土卫六表面的地质过程和化学成分，这反过来有助于我们理解土卫六是如何演化的，其表面是如何持续变化的，以及其宜居性的程度。 先前的研究表明，在特定温度和实验条件下会形成一种吡啶：乙炔（1:1）共晶体；然而，这种现象尚未在与土卫六相关的情况下得到验证。 我们的研究在此基础上证明，吡啶：乙炔共晶体在90K（土卫六的平均表面温度）到180K的氮气气氛下是稳定的。特别是在150K时，通过液体-固体相互作用，组分混合后几分钟内即形成共晶体，这一结论由独特的新的拉曼光谱带及带移所证实。 XRD结果显示，在90-150K之间，沿三个主轴方向存在适度的各向异性热膨胀（约0.5%-1.1%）。 此外，在暴露于液态乙烷之后，共晶体仍可被检测到，这表明它在残余乙烷“润湿”场景中的稳定性。这些结果表明，吡啶：乙炔共晶体可能在土卫六上某些允许温暖环境存在的地质环境中形成，其中液态吡啶可以持续存在，因此，这种低温矿物可能会保存地表物质中撞击、冰火山活动或地下运输的证据。 显示英文摘要

摘要： Titan, Saturn's largest moon, has a plethora of organic compounds in the atmosphere and on the surface that interact with each other. Cryominerals such as co-crystals may influence the geologic processes and chemical composition of Titan's surface, which in turn informs our understanding of how Titan may have evolved, how the surface is continuing to change, as well as the extent of Titan's habitability. Previous work has shown that a pyridine:acetylene (1:1) co-crystal forms under specific temperatures and experimental conditions; however, this has not yet been demonstrated under Titan-relevant conditions. Our work here demonstrates that the pyridine:acetylene co-crystal is stable from 90 K, Titan's average surface temperature, up to 180 K under an atmosphere of N2. In particular, the co-crystal forms via liquid-solid interactions within minutes upon mixing of the constituents at 150 K, as evidenced by distinct, new Raman bands and band shifts. XRD results indicate moderate anisotropic thermal expansion (about 0.5% - 1.1%) along the three principal axes between 90-150 K. Additionally, the co-crystal is detectable after being exposed to liquid ethane, implying stability in a residual ethane "wetting" scenario on Titan. These results suggest that the pyridine:acetylene co-crystal could form in specific geologic contexts on Titan that allow for warm environments in which liquid pyridine could persist, and as such, this cryomineral may preserve evidence of impact, cryovolcanism, or subsurface transport in surface materials.