Real-time investigation on the melting dynamics of aromatic molecular crystals by using fast Low-frequency Raman spectroscopy

结果表明，在菲的熔融过程中，存在着一种过渡晶体结构。“过热”晶体的晶格振动不同于静止状态的晶格振动，这种晶格振动只在熔化过程中才能看到。我们对快速低频拉曼光谱进行了改进，使其可以在显微镜下同时监测样品的光学图像。它能够以亚秒级的时间分辨率和微米级的空间分辨率追踪晶格振动的出现(或消失)，同时监测晶格形态的变化。这将为在分子水平上实时跟踪小晶体相变过程中的结构变化提供一种新的方法。

We showed that a transient crystalline structure of anthracene exists in its melting. Lattice vibrations of the'' super-heated'' crystal, which is only seen during the melting, are different to those of the stationary state. We improved the fast low frequency Raman spectroscopy for simultaneous monitoring the optical image of the sample under microscope. It enables sub-second time-resolved and micrometer space-resolved tracing of the appearance(or disappearance) of lattice vibrations with simultaneous monitoring the morphology changes. It will be a new method for molecular-level and real-time tracing structural change of a small crystal during its phase transitions.