ULTRAFAST TRANSIENT SOLVATION OF POLAR DYE MOLECULES IN SIMPLE POLAR SOLVENTS

$^{1}$ M.A. Kahlow. T.J. Kang and P.F. Barbara. J. Chem. Phys. 88. 2372 (1988); M.A. Kahlow. W. Jarzeba. T.P. DuBruil and P.F. Barbara. Rev. Sci. Instrum. (in press). $^{2}$ E.W. Castner. G.R. Fleming and B. Bagchi. Chem. Phys. Lett. (in press). $^{3}$ P.G. Wolynes. J. Chem. Phys. 86. 5133 (1987).Author Institution: Department of Chemistry, University of Minnesota,Recently we constructed a time resolved fluorescence apparatus with a resolution of less than 300 femtoseconds1. We have used this instrument to measure the microscopic solvation dynamics of three simple polar solvents (propylene carbonate, propiontrile, and methanol) by observing the time resolved fluorescence from coumarin 152. The solvation rates are non-singly exponential, with components both shorter and longer than the longitudinal relaxation times r1 of the solvents. Results will be discussed in terms of several recent theoretical $models^{2-3}$