Search

A study of photochemical deactivation pathways of electronically excited methyl viologen (1,1'-dimethyl-4,4'-bipyridinium, MV2) in several polar solvents at room temperature using a variety of ultrafast time-resolved and steady-state spectroscopic techniques is done. Unexpectedly diverse behavior of methyl viologen in different polar solvents is reported.

A study was conducted to analyze the ultrafast photoionization characteristics of indole in water. A white-light continuum probe pulse was utilized to obtain transient absorption measurements. Pump and probe beams were crossed in a free-flowing jet of the liquid sample. Results indicated that the bimolecular reaction between indole radical cations and solvated electrons were slower than the diffusion limit.

The dynamics of the first singlet excited state decay of I-nitronaphthalene through intersystem crossing to the triplet manifold in a series of solvents is demonstrated. Both the excited state of the I-NN molecule is found to be [pi]-[pi]* type with some aromatic-to-nitro charge-transfer character.

The femtosecond fluorescence up-conversion studies which were carried out to characterize the excited state enol to cis-keto tautomerization through measurements of the transient molecular emission are reported.

The resolved emission measurements of the singlet excited states are presented which are the precursors in the electronically exited nitrated polycyclic aromatic hydrocarbons (NPAHs). Results show that NPAHs have the largest intersystem crossing rates in an organic molecule.

Key issues macromolecular hydration with emphasis on proteins in the native and dematured state, and micelles. A simple theory, which relates the observations of solvation to the residence times on the protein surface and address the influence of dielectric relaxations, by rotational and translational motions, on the dynamics of bound-to-free water exchange.