Real-Time Studies of Negative Ion Photodissociation and Reaction Dynamics

在化学系物理化学计划的这个项目中，加州大学伯克利分校的D.Neumark教授将实时研究负离子的光解离和反应动力学。在飞秒激光脉冲作用下，负离子AB-被激发到解离电子态。第二个飞秒激光脉冲相对于第一个脉冲时间延迟，导致解离离子的光分离，并记录产生的光电子能谱。这个程序允许观察初始激发物种的衰变，确定各种阴离子产物的出现时间，并测量它们的内部能量分布。将研究多原子阴离子O_3~-、CO_3~-和I_3~-。还将研究涉及这些单体阴离子单元的团簇阴离子。虽然负离子在大气和溶液相化学中扮演着重要的角色，但人们对光解离和反应动力学的细节知之甚少。这项研究的目的是通过使用最先进的超快激光技术来跟踪负离子解离或反应的时间演变，以更好地了解这些过程。

In this project in the Physical Chemistry program of the Chemistry Division, Prof. D. Neumark of the University of California at Berkeley will study the photodissociation and reaction dynamics of negative ions in real time. A negative ion AB- is excited to a dissociative electronic state by a femtosecond laser pulse. A second femtosecond laser pulse, time delayed with respect to the first, causes photodetachment of the dissociating ion and the resulting photoelectron spectrum is recorded. This procedure the permits observation of the decay of the initially excited species, the determination of the appearance times of the various anion products, and the measurement of their internal energy distribution. The polyatomic anions O3-, CO3- and I3- will be investigated. Also studied will be cluster anions involving these monomer anion units. Although negative ions play important roleq in atmospheric and solution phase chemistry, the details of the photodissociation and reaction dynamics are poorly understood. The goal of this research is to obtain a better understanding of these processes by using state-of-the-art ultrafast laser techniques to track the time evolution of the dissociation or reaction of a negative ion.