Picosecond Time-Resolved Resonance Raman Study of the Solvated Electron in Water

Abstract

Picosecond time-resolved Raman spectra of water were measured under the resonance condition with the electronic transition of the solvated electron. Transient Raman bands were observed in the OH bend and the OH stretch regions in accordance with the generation of the solvated electron. The lifetimes of the transient Raman bands were shortened by the addition of the electron scavenger, in exactly the same manner as the solvated electron absorption. It was concluded that the observed transient Raman bands are attributed to the water molecules that directly interact with the electron in the first solvation shell. The resonance enhancement factors were estimated as high as ∼105 (the OH bend) and ∼103 (the OH stretch) when the probe wavelength was tuned to the absorption maximum of the s → p transition of the solvated electron. The observed very high resonance enhancement indicated that the vibrational state of the solvating water molecules is strongly coupled with the electronic state of the electron. This im...