Aqueous solvation dynamics studied by photon echo spectroscopy

Three-pulse photon echo peak shift measurements were employed to study aqueous solvation dynamics. A new perspective of dielectric continuum theory [X. Song and D. Chandler, J. Chem. Phys. 108, 2594 (1998)] aided in characterizing the system-bath interactions of eosin in water. Application of this theory provides solvation energies, which were used within the spectral density representation rho(omega), to calculate the experimental peak shift. Simulations with only solvation contributions to rho(omega), where a substantial amplitude of the solvation occurs within similar to 30 fs, are remarkably consistent with our data. Furthermore, simulations using this theoretical solvation spectral density and an experimentally determined intramolecular spectral density yield an excellent total simulation of the peak shift data over the entire dynamic range. Our experimental results substantiate predictions that interaction-induced polarizability effects, contributing via a similar to 180 cm(-1) band in the spectral density, influence the initial dynamics. (C) 1999 American Institute of Physics. [S0021-9606(99)50312-7].