Femtosecond Nonlinear Spectroscopic Studies of Chemical Reactions in Condensed Phases

在这个由实验物理化学计划支持的项目中， 在化学部，乔纳斯将学习的基本步骤， 溶液中的化学反应 两种新型多脉冲 飞秒非线性光谱学将被开发，以解决 液体中分子无特征光谱下的动力学。 一种技术将使用三脉冲序列来准备和研究 热活化化学反应的过渡态 分辨率大约为20飞秒。 第二种方法将 从四波混频中获得完整的电场信息 通过使用光谱的外差检测的诸如光子回波的信号 干涉测量法 实验将研究溶剂的作用， 烷基碘的单分子离子解离，目的是 确定单分子离子解离是否被激活 溶剂波动或分子内振动激发。 溶剂对化学反应的速率有显著的影响。 他们 通过改变溶质分子的内部能量结构， 改变反应机理或允许新的反应路径。 在 本项目将在实验中使用两种新的实验技术 其目的是探索溶剂对几种不同的 反应的类型，例如那些通过增加 温度 这些研究的结果应该可以帮助我们理解 重要的溶剂效应存在于这些不同的反应中。 等 知识可以帮助确定反应的条件， 应运行解决方案以获得最佳预期结果。

In this project supported by the Experimental Physical Chemistry Program of the Chemistry Division, Jonas will study the elementary steps of chemical reactions in solution. Two new types of multiple-pulse femtosecond nonlinear spectroscopy will be developed in order to resolve the dynamics beneath the featureless spectra of molecules in liquids. One technique will use a three-pulse sequence to prepare and study transition states for thermally activated chemical reactions with a time resolution on the order of 20 femtoseconds. The second method will obtain the complete electric field information from four-wave mixing signals such as the photon echo by heterodyne detection using spectral interferometry. Experiments will study the role of the solvent in the unimolecular ionic dissociation of alkyl iodides with the aim of determining whether unimolecular ionic dissociation is activated by solvent fluctuations or intramolecular vibrational excitation. Solvents have dramatic effects on the rates of chemical reactions. They do this by altering the internal energy structure of solute molecules, changing the reaction mechanisms, or allowing new reaction paths. In this project two new experimental techniques will be used in experiments which are designed to probe the effect of solvents on a few different types of reactions, such as those which are expedited by increasing temperature. The results of these studies should help us understand how important solvent effects are in these different reactions. Such knowledge can help determine the conditions under which reactions in solution should be run for optimal desired results.