Ruth E. Riter

Influence of restricted environment and ionic interactions on water solvation dynamics

Polar solvation dynamics of water sequestered inside Aerosol OT (AOT) reverse micelles have been investigated as a function of the surfactant countercation, specifically replacing Na+ for K+ and Ca2+. For Ca-AOT reverse micelles, the solvation dynamics for the smallest micelles probed occurs on a subnanosecond time scale. The K-AOT reverse micelles display an additional ultrafast component that is attributable to bulklike water motion. As previously reported for Na-AOT reverse micelles [Riter, Willard, and Levinger, J. Phys. Chem. B 102, 2705 (1998)], solvent mobility increases with increasing micellar size for both Ca-AOT and K-AOT reverse micelles. The solvation dynamics in strongly ionic aqueous solutions of Ca2+ and K+ have also been investigated. The 10 M electrolyte solutions display water motion on significantly shorter time scales with substantial ultrafast components. These results show that the micellar interfacial structure plays a significant role in immobilizing intramicellar water and that s...

RADIATIONLESS DECAY FROM THE LIGAND-TO-METAL CHARGE-TRANSFER STATE IN THE BLUE COPPER PROTEIN PLASTOCYANIN

Abstract The cysteine S(p π ) → Cu 2+ d x 2 − y 2 ligand-to-metal charge-transfer (LMCT) state in plastocyanin exhibits a time-resolved pump-probe spectrum that has excited-state absorption and stimulated-emission components to the blue and red, respectively, of the absorption maximum. The LMCT state returns to the ground state by populating the d xz + yz → d x 2 − y 2 ligand-field (LF) state. The lack of hole-burned features in the time-resolved spectra implies the presence of intramolecular vibrational redistribution and/or protein-matrix solvation dynamics on a time scale that is shorter than the 125 fs lifetime of the LMCT state.

Solvation Dynamics in Restricted Environments: Solvent Immobilization in Reverse Micelles

Polar solvation dynamics in various reverse micellar environments are investigated. The solvent is immobilized in the smallest micelles and becomes more mobile with increasing water content and micellar size.

Inertial Protein-Matrix Solvation of a Light-Harvesting Chromophore

We have employed transient hole-burning spectroscopy (THB) to characterize ultrafast protein-matrix solvation processes in the α subunit of the cyanobacterial light-harvesting protein C-phycocyanin.