In solution-phase reactions, interactions with the solvent can dictate not only which products form but also the rate at which they are formed. Understanding these interactions is vital to understanding any solution-phase reaction at a fundamentalMoreIn solution-phase reactions, interactions with the solvent can dictate not only which products form but also the rate at which they are formed.
Understanding these interactions is vital to understanding any solution-phase reaction at a fundamental level. For most reactions, solvent motions are complicated and the dynamics that are due solely to solvent interactions are difficult to extract. In this thesis I present the results of experiments in which I use the ultrafast pump--probe spectroscopy of atomic anions and the solvated electron (an excess electron in solution) to explore the solvation response to a change in the solutes properties induced by an excitation pulse.
Since atomic anions and the solvated electron have no nuclear degrees of freedom, all of the dynamics observed must be due to solvent motions alone. For the solvated electron, my polarized pump--probe anisotropy experiments demonstrate that the solvent motions that scramble the electrons excited states are faster than has been predicted theoretically. My experiments on sodide in tetrahydrofuran (THF) reveal that the relaxation process for a neutral atom left behind when an electron is ejected from sodide is decoupled from the excited electrons relaxation dynamics.
The initially created gas-phase-like sodium atom undergoes a fast solvation, followed by a reaction to form an unequilibrated sodium cation/electron tight contact pair (TCP) that equilibrates on a very slow time scale.
I examine this reaction in a series of linear ether solvents that are similar in chemical structure but that differ in ether chain length and find that the dynamics observed in these different solvents are very similar to the dynamics observed in THF. The dynamics suggest that these other ether solvents likely contain positively charged cavities similar to those previously observed in THF [1--3]. I also compare the CTTS dynamics of potasside and sodide in diethyl ether (DEE).
I find that the subtle differences I observe in the dynamics allow me to explore the density of solvent-supported electronic excited states of DEE and to determine the difference in solvation energies between sodide and potasside in DEE.