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.
