In this award, funded by the Experimental Physical Chemistry Program of the Division of Chemistry, Professor W. Carl Lineberger of the University of Colorado, together with his postdoctoral, graduate and undergraduate student researchers, will study the time-resolved photoelectron spectra of a number of anions/radicals in solvent cages, as well as anions whose photoionization result in radicals with multiple radical centers. Some of the interesting molecular anions to be studied include HOOO- and 1,3,5 dehydrobenzene anion.
The particular molecular systems chosen for study are of broad interest to the scientific community. The research of the Lineberger group will have impact in the fields as diverse as polymer science and atmospheric chemistry. A number of the molecular targets will provide useful data with which to challenge computational chemists. In addition to training advanced research students, Prof. Lineberger will continue in his leadership of the Science Education Initiative on his campus. This program brings undergraduate students in selected courses into research laboratories for short periods of time during the academic year.
A major goal of research in physical chemistry is to develop methods to influence the trajectory of chemical reactions, so as to both understand the details of the reaction mechanism and, importantly, find methods to influence reactions along their reaction path, with the intent of leading a reaction to the desired outcome. The most sensitive point along a chemical reaction pathway is a region which is neither reactants nor products. It is the energetic high point of a reaction path and is called the transition state. This work is leading to the development of negative ion-based methods to obtain spectra of reactive complexes not just at the transition state, but also as a function of time along the entire reaction coordinate. In order to carry out such studies, it is necessary to use techniques that can capture the structure of an evolving reaction in and ultrafast snapshot as well as techniques that in lower resolution follow a reaction complex as a function of time. We have continued and extended our innovative uses of negative ions and their clusters to obtain new insights into the most fundamental areas of molecular reaction dynamics. In a variety of experiments, the researchers supported by this grant exploit the idea that the "extra" electron on a negative ion is a "light and ultrafast" spectator that can be removed rapidly by laser radiation, initiating chemical reactions or producing neutral molecular spin states generally inaccessible by conventional approaches. New projects in anion photoelectron spectroscopy, solvation of discharge particles and trapping of reactive intermediates at a transition state are some of the principal accomplishments during this grant. Two major thrust concern the evolution to ever larger molecular complexes which can play a key role in atmospheric and interfacial chemistry. While this grant supports directly one postdoctoral research associate, two graduate students and an undergraduate student, the key to its success is the development of a collaborative enterprise involving major theoretical scientist from many countries. It is this combination of state-of-the-art experiment with state-of-the-art theory that enables a steady progression toward more complete understanding of ever more complex and potentially directly applicable chemical systems. Another important aspect of this program is that essentially every project involves collaborations with other, complementary,experimental groups and with leading theoreticians. This collaborative environment provides an exceptional, multidisciplinary atmosphere for the development of graduate students and postdoctoral associates.
