Enhanced Translational Diffusion and Spatially Heterogenous Dynamics in Supercooled Liquids

牛津大学化学系的Mark Ediger教授 威斯康星-麦迪逊大学得到了理论和 计算化学程序进行实验表征 过冷有机液体的玻璃化转变， 许多多环芳烃化合物，如蒽、并四苯4、红荧烯 和衍生品。实验被提议调查的性质 分子运动在深过冷有机液体探测 液体/玻璃化转变的性质。这项研究的问题是， 将解决的问题是：（1）什么类型的分子运动发生在深层 过冷液体;（2）过冷液体是空间的吗 （3）这是如何与非指数联系起来的？ 经常观察到的放松。光学、介电和NMR 光谱学将被用来回答这些问题，特别是， 不同温度的地区寿命有多长， 非指数动力学和异质性之间的联系， 非均匀动力学与观测到的 平移的增强，并且如果各向异性运动是 负责加强翻译。 尽管在分子解释方面取得了重大进展， 液态的静态和动态性质， 在玻璃化转变附近发生的液体和分子运动 温度，还没有很好的理解。 这些实验 由埃德加进行的研究旨在揭示这些问题， 异常旋转和交易松弛，以及 玻璃化转变中的空间不均匀动力学。

Professor Mark Ediger of the Department of Chemistry of the University of Wisconsin-Madison is supported by a grant from the Theoretical and Computational Chemistry Program to perform experimental characterizations of the glass transition in supercooled organic liquids which include a number of polyaromatic compounds such as anthracene, tetracene4, rubrene and derivatives. Experiments are proposed to investigate the nature of molecular motion in deeply supercooled organic liquids to probe the nature of the liquid/glass transition. The questions that this research will address are: (1) What types of molecular motions occur in deeply supercooled liquids; (2) Is the supercooled liquid spatially heterogeneous; and (3) how is this connected to the non-exponential relaxation that is often observed. Optical, dielectric and NMR spectroscopies will be used to answer these questions, and in particular, how long-lived are the regions of different temperature, what is the connection between non-exponential dynamics and heterogeneity, what is the connection between heterogeneous dynamics and the observed enhancement of translation and if the anisotropic motion is the responsible for enhanced translation. In spite of the significant progress in the molecular interpretation of the static and dynamic properties of the liquid state, the properties of liquids and the molecular motions which occur near the glass transition temperature, are still not well understood. The experiments being conducted by Edgar are designed to shed light these problems, on the anomalous rotational and transactional relaxation, and the role of spatially inhomogeneous dynamics in the glass transition.