Ultrafast Laser Spectroelectrochemistry

在这个由化学系化学测量和成像项目资助的项目中，伊利诺伊大学的Dana Dlott教授正在开发先进的基于激光的仪器，用于探测电化学转化过程中电极表面上的分子。燃料电池和电池等电化学系统构成了工业经济的重要组成部分，但事实证明，很难理解这些过程在单个分子的基础水平上是如何工作的。更深入的基本理解产生了电化学科学重大新进展所需的知识。研究人员用光学窗口制造电池和燃料电池，并将激光束照射在电极上，以观察分子在真实的时间内的行为。然而，有一个主要的问题;对于电极上发生化学反应的每个分子，大约有10亿个旁观者分子没有做任何感兴趣的事情。为了解决这个问题，研究人员正在开发一种方法，包括脉冲激光束和计算机控制激光波长。这使得激光束可以忽略旁观者分子，因此研究人员可以看到化学反应是如何在电化学反应器深处发生的。这项工作将对新技术的开发产生广泛的影响，这些新技术将提高燃料电池和电池等设备的性能。通过让研究生和本科生参与科学研究，它正在对下一代科学家的培训产生更广泛的影响。该项目包括两个相关的努力，开发仪器的电化学光谱探测使用非线性相干红外（IR）光谱方法称为和频发生（SFG）。SFG是研究埋置界面（如埋置在厚电解质层下的电极）化学的最有效方法之一。第一个努力旨在提高的能力，以获得SFG光谱在掩埋的接口，通过克服时间和频率失真的FS IR脉冲通过IR窗口和电解质。计算机控制的红外脉冲整形技术被用来预失真的红外脉冲，使他们到达不失真的电极。第二个努力是开发仪器，研究超快分子动力学在电极上的超快激光温度跳跃的电极，同时探测吸附的分子SFG。在电化学电池中，相当小（50 K）的温度跳变可对电极电位产生显著影响（100 mV）。温度跳跃方法是一种快速（以纳秒为单位）跳跃电极电位的方法，其速度远远快于电学方法。

In this project funded by the Chemical Measurement and Imaging program in the Division of Chemistry, Prof. Dana Dlott of the University of Illinois is developing advanced laser-based instruments that probe molecules on the surfaces of electrodes during electrochemical transformations. Electrochemical systems such as fuel cells and batteries form a significant part of our industrial economy, yet it has proven difficult to understand how these processes work at the fundamental level of individual molecules. A deeper fundamental understanding produces the knowledge needed for major new advances in electrochemical sciences. The investigators build batteries and fuel cells with optical windows, and shine laser beams at the electrodes to watch how the molecules behave in real time. There is a major problem, though; for every molecule at the electrode where the chemistry takes place, there are about one billion spectator molecules not doing anything of interest. To address this problem, the investigators are developing methods that involve pulsing the laser beams and controlling the laser wavelengths by computers. This allows the laser beams to ignore the spectator molecules so the researchers can see how chemistry takes place deep inside electrochemical reactors. The work will have a broad impact on the development of new technologies that will enhance the performance of devices such as fuel cells and batteries. It is having a further broad impact on the training of the next generation of scientists, by involving students at the graduate and undergraduate level in scientific research. The project consists of two related efforts to develop instruments for spectroscopic probing of electrochemistry using a nonlinear coherent infrared (IR) spectroscopy method termed sum-frequency generation (SFG). SFG is one of the most powerful methods to study chemistry at buried interfaces such as electrodes buried under thick electrolyte layers. The first effort seeks to improve the ability to obtain SFG spectra at buried interfaces by overcoming temporal and frequency distortions of fs IR pulses passing through an IR window and an electrolyte. Computer-controlled IR pulse-shaping techniques are used to predistort the IR pulses so they arrive undistorted at the electrodes. The second effort seeks to develop instruments to study ultrafast molecular dynamics at electrodes by ultrafast laser temperature jumping of the electrodes while probing the adsorbed molecules by SFG. In an electrochemical cell, a rather small (50 K) temperature jump can have a significant effect (100 mV) on the electrode potential. The temperature-jump method is a way to rapidly (in nanoseconds) jump electrode potentials far faster than is possible by electrical methods.