Novel precursors of solvated electrons in water: Evidence for a charge transfer process

Femtosecond midinfrared spectroscopy of water (heavy water) after two photo n excitation at 9 eV provides clear evidence for two short-lived precursors of the hydrated electron preceding the well-known "wet electron." The meas ured first intermediate with peak absorption at 2.9 (4.1) mu m is proposed to represent an O(H,D):e(-) complex. The subsequent solvation proceeds via e(-):[(H,D)(2)O](n) complexes at approximately 1.6 (2.0) mu m in the electr onic ground state, involving an increasing number of water molecules during the first 200 fs and followed by the wet electron.