Multidimensional Methods for Measuring Kinetics in Complex Materials

在化学系化学测量和成像项目的支持下，哥伦比亚南卡罗来纳大学的Berg教授正在开发新的多维光谱方法来研究反应速率（动力学），并将新技术应用于具有复杂分子动力学的材料。在简单的材料中，化学反应或过程可以通过实验解析为基本步骤，每个步骤都有明确的速率。当一种物质由复杂分子或分子组合组成时，这些基本步骤往往表现为速率的扩散。伯格教授的实验室正在开发的多维方法有助于确定导致速率扩散的状态的性质和寿命。在这里开发的方法扩展到生物，化学，材料科学和工程的广泛过程和材料。伯格教授与研究生和本科生密切合作，开发这些表征物质的复杂方法。他还参与了一些创造性的方法，以吸引来自代表性不足的少数群体的学生参与研究项目。三个子项目分别解决不同的材料、动力学问题和技术挑战。插入微结构材料的探针分子的旋转速率目前用于测量结构内特定点的局部粘度。这些实验通常产生一系列的旋转速率。目前正在进行六脉冲偏振光学实验，以确定这个范围是由微观结构的变化还是由结构的局部各向异性引起的。绿色荧光蛋白（GFP）是了解蛋白质内部反应动力学的原型。一种多色、多维度的光学实验正在开发中，以确定在GFP动力学中观察到的多重速率是由于多种蛋白质底态还是由于光循环中未解决的中间步骤。人们正在开发分析计算机模拟的多维方法，以了解液体冷却时液体内部长寿命结构的形成。虽然实验可以在低温下看到这些效应，但模拟是目前探测它们在高温下初始形成的最佳方法。伯格教授不仅打算促进对分子反应动力学的基本理解，而且还打算为学生提供跨学科的培训经验，特别是那些来自代表性不足的少数群体的学生。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Berg at the University of South Carolina at Columbia is developing new multidimensional spectroscopic methods to study reaction rates (kinetics) and apply the new techniques to materials with complex molecular dynamics. In simple materials, chemical reactions or processes can be experimentally parsed into fundamental steps, each with a well-defined rate. When a material is composed of complex molecules or molecular assemblies, these fundamental steps often appear to have a spread of rates. The multidimensional methods being developed at the Professor Berg's lab help to determine the nature and lifetime of states which cause the spread of rates. The methods being developed here extend to a wide range of processes and materials in biology, chemistry, materials science and engineering. Professor Berg works with graduate and undergraduate students closely on the development of these complex methods of characterizing matter. He is also involved in a number of creative approaches to engage students from underrepresented minority groups in the research project. Three subprojects each address a different material, kinetic problem and technical challenge. The rotation rates of probe molecules inserted into microstructured materials are currently used to measure local viscosity at specific points within the structure. These experiments often yield a range of rotational rates. Six-pulse, polarized optical experiments are being developed to determine whether this range is caused by variability in the microstructure or by local anisotropy in the structure. The green-fluorescent protein (GFP) is a prototype for understanding reaction dynamics within a protein. A multicolor, multidimensional, optical experiment is being developed to determine if the multiple rates observed in GFP kinetics are due to multiple protein substates or due to unresolved intermediate steps in the photocycle. Multidimensional methods of analyzing computer simulations are being developed to understand the formation of long-lived structures within liquids as the liquid is cooled. Although experiments can see these effects at low temperatures, simulations are currently the best approach to probing their initial formation at higher temperatures. Professor Berg intends not only to advance fundamental understanding about molecular reaction kinetics but also to provide students an interdisciplinary training experience, in particular those students from underrepresented minority groups.