This award is made in the Organic Dynamics Program in support of the research of Dr. Charles Doubleday. Both computational and time-resolved experimental studies of the dynamics of bimolecular reactions which have low or zero enthalpies will be carried out. Specific computational studies will focus on reactions of singlet ethylene and methylene with ethylene, water and ammonia, as well as the competition between combination and disproportionation in the reaction of methyl and ethyl free radicals. Ab initio calculations of reaction potential curves will be combined with variational transition state theory to derive reaction rate constants. Experimentally, picosecond pump-probe spectroscopy of intramolecular entropy-controlled reactions of biradicals will be explored. The dependence of the transient decay trace on temperature and solvent viscosity will be determined. Entropy-controlled bimolecular reactions such as carbene trapping , reaction of ylides with olefins, singlet oxygen trapping, radical recombination, cycloadditions and excited-state quenching are common in organic chemistry. This research will advance our understanding, both on a theoretical and experimental level of the dynamics of these important processes.
