Femtosecond Pump-Probe-Spectroscopy of the Solvated Electron in Water and Aqueous Salt Solutions

Abstract

Transient pump-probe experiments on the equilibrated, solvated electron in pure water and aqueous NaCl solution are carried out with femtosecond time resolution. A deconvolution of the experimental data using a 5-level scheme results in the following features: A first absorption spectrum appears immediately after excitation which can be attributed to a frequency shifted excited p’-state. The first relaxation inbetween the p-states and/or the reorganisation of the solvation shell occures on a timescale <80 fs. After an internal conversion p’ → s” with 230 ± 40 fs the solvent surrounding cools down on a charactristic timescale of 1.35 ± 0.15 ps. The corresponding timeconstants in pure water are merkedly accelerated.