Studies of negative ion spectroscopy and dynamics using time resolved photoelectron imaging

在这个由化学系实验物理化学计划资助的项目中，加州大学伯克利分校的丹尼尔·纽马克将通过基于飞秒泵浦-探测技术的时间分辨光电子成像（TRPEI）对负离子和负离子团簇进行光谱和动力学研究。 该方法是基于在以前的资助下所做的成功工作，现在扩展到时间分辨率领域。 具体来说，飞秒受激发射泵浦将用于相干激发集群负I2离子，TRPEI将用于跟踪产生的振动弛豫和溶剂蒸发动力学。 时间分辨泵浦-探测实验将探测团簇中电子溶剂化的动力学。 还计划对双分子离子-分子反应，特别是气相SN 2反应进行时间分辨研究，方法是用飞秒泵浦脉冲光引发反应，并通过时间分辨光电子能谱监测随后的动力学。 工作的重点是理解光剥离动力学和团簇动力学过程。 这项研究将与博士后研究助理和研究生以及本科生一起进行，他们通过参与前沿，前沿的研究课题，将接受先进研究技术的培训，为美国经济的工业，学术或政府部门的就业做准备。

In this project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Daniel Neumark of the University of California at Berkeley will engage in spectroscopic and dynamical studies of negative ions and negative ion clusters by means of time-resolved photoelectron imaging (TRPEI) based on femtosecond pump-probe techniques. The approach is based on the successful work done under the previous grant, which is now extended into the domain of time resolution. Specifically, femtosecond-stimulated emission pumping will be used to coherently excite clustered negative I2 ions, and TRPEI will be used to track the resulting vibrational relaxation and solvent evaporation dynamics. Time-resolved pump-probe experiments on halide-water clusters will probe the dynamics of electron solvation in clusters. Time-resolved studies of bimolecular ion-molecule reactions, in particular gas-phase SN2 reactions, by photoinitiating a reaction with a femtosecond pump pulse and monitoring the subsequent dynamics by time-resolved photoelectron spectroscopy are also planned. The focus of the work is to understand the processes of photodetachment dynamics and cluster dynamics. This research will be conducted with postdoctoral research associates and graduate students, as well as undergraduates, who, through their participation in a forefront, cutting-edge research topic, will receive training in advanced research techniques in preparation for employment in the industrial, academic, or governmental sectors of the American economy.