Direct probing of low frequency motions in solution phase chemical dynamics

在这个由化学部门实验物理化学计划资助的项目中，David Blank将开发和应用新的实验方法，旨在解决分子间和低频分子内核运动在凝聚相反应和非反应化学动力学中的作用。这些实验利用了多维飞秒光谱技术，根据各自提供的互补信息可分为两类。首先，利用超快激光脉冲光引发溶液中动态事件的低频运动响应，并利用三阶时域拉曼光谱监测响应。其次，将使用一种新的共振增强版相干二维时域拉曼光谱直接测量凝聚系统中低频运动之间的耦合。这些研究有望对液相化学反应中的低频运动提供新的见解。从工业反应到生物化学，大部分化学反应都是在溶液中进行的。该项目旨在提供溶液中化学反应性的微观描述，这是当今物理化学的核心问题之一。建议的方法是直接和普遍适用的技术，将有助于理解所涉及的科学问题。这项工作的应用范围从现代光学和计量到先进材料表征和凝聚态物质的基础研究。作为这项研究工作的一部分，从本科生到博士后水平的学生都接受了超快激光技术的最先进仪器的培训，这是物理科学的新兴领域。

In this project funded by the Experimental Physical Chemistry Program of the Chemistry Division, David Blank will develop and apply novel experimental methods designed to address the role of intermolecular and low frequency intramolecular nuclear motions in condensed-phase reactive and nonreactive chemical dynamics. The experiments utilize multidimensional femtosecond spectroscopic techniques, and can be divided into two types, based on the complementary information each will provide. First, the response of low frequency motions in response to the progress of a dynamic event in solution will be probed by photo-initiating that event with an ultrafast laser pulse, and monitoring the response using third-order time domain Raman spectroscopy. Second, the coupling between low frequency motions in condensed systems will be directly measured using a new resonance enhanced version of coherent two-dimensional time domain Raman spectroscopy. These studies are expected to enable new insights into low frequency motions in solution phase chemical reactions.The significant proportion of chemistry, from industrial reactions to the chemistry of biology, takes place in the solution phase. This project aims at providing a microscopic description of chemical reactivity in solution, one of the central issues in physical chemistry today. The proposed methods are direct and generally applicable techniques that will aid in understanding the scientific issues involved. This work has applications ranging from modern optics and metrology to advanced materials characterization and fundamental research in condensed matter. As part of this research effort, students from the undergraduate through the postdoctoral level are trained with state-of-the-art instrumentation in ultrafast laser technology, an emerging field in the physical sciences.