Nanoscale Fluctuations in Disordered Materials

摘要无论是普通材料还是特殊材料，在制造超小型机器时都会表现出意想不到的行为。正常的性质，如机械强度和导电性，在这种只有几十亿分之一米大小的物体中可能会发生巨大的变化。了解空间异质性和时间波动对纳米技术很重要。无序固体（玻璃）、塑料和具有非凡弹性的高级金属是具有重要技术意义的材料的原型。当一种材料经历从液体到玻璃态的变化时，纳米性质在不同的位置上波动很大。使用强大的新显微技术，这些波动将被成像和研究，并用于测试玻璃形成的新理论。这项工作的最终目标将是预测纳米技术的纳米材料组成部分的性质，以及新的无序材料类别。本科生将通过研究和结合最新技术的新课程参与该项目。技术摘要复杂材料在纳米尺度上可能表现出性质的变化。理解这些波动对于纳米技术将变得越来越重要。在玻璃化转变附近，无序材料被认为具有较大的空间和时间波动（动力学异质性），这在玻璃化现象中起着核心作用，如缓慢的非指数弛豫和老化。利用基于超高真空电磁力显微镜的新型纳米成像技术，研究聚合物和简单液体在玻璃化转变附近的实时时空波动和局部介电响应函数。这些研究将使动态异质性的模式和统计特性可视化，从而测试有前途的玻璃化转变新模型。通过研究温度淬火后的波动和响应，非平衡统计力学中的新思想将得到检验。本科学生将通过参与这项研究，并通过一个新的实验课程，包括最新的测量技术，为高级本科生和研究生提供纳米科学方面的培训。

Non-Technical AbstractBoth exotic and ordinary materials exhibit unexpected behavior when they are used to build ultra-small machines. Normal properties, such as their mechanical strength and electrical conductivity, may in fact vary dramatically in such objects that are a few billionths of a meter in size. Understanding of spatial heterogeneity and temporal fluctuations is important for nanotechnology. Disordered solids (glasses), plastics, and advanced metals with extraordinary springiness are prototype examples of materials that are technologically important. When a materials is undergoing a change from a liquid to a glassy state, nano-properties are believed to fluctuate wildly in different locations. Using powerful new microscopic techniques, these fluctuations will be imaged and studied, and used for testing new theories of glass formation. The ultimate goal of this work will be to predict the properties of the nano-material building blocks of nanotechnology, as well as new classes of disordered materials. Undergraduate students will participate in this project through research and a new course that incorporates the latest techniques.Technical AbstractComplex materials may exhibit variations in their properties on the nanoscale. Understanding these fluctuations will be increasingly important for nanotechnology. Near the glass transition, disordered materials are believed to have large spatial and temporal fluctuations (dynamical heterogeneity), which play a central role in glassy phenomena such as slow, non-exponential relaxation and aging. Using new nanoscale imaging techniques based on ultra-high-vacuum electric force microscopy, the real-time spatio-temporal fluctuations as well as local dielectric response functions will be studied in polymers and simple liquids near the glass transition. These studies will enable the visualization of the pattern and statistical properties of dynamical heterogeneity, thereby testing promising new models of the glass transition. By studying fluctuations and responses following a temperature quench, new ideas in non-equilibrium statistical mechanics will be tested. Undergraduate students will be trained in nano-science by their participation in this research and through a new experimental course for advanced undergraduate and graduate students which incorporates the latest measurement techniques.