Ultrafast electron trapping in an aqueous NaCl-solution

The generation of solvated electrons in an aqueous solution of sodium chloride is studied by femtosecond pump-probe absorption spectroscopy in the VIS and NIR with polarization resolution. Our data give evidence that the photo detachment of electrons occurs via two photon absorption of intense 200 fs pump pulses at 310 nm to an excited charge-transfer-to-solvent (CTTS) state of the halide anion. The subsequent relaxation dynamics involves the population of the CTTS ground state with a time constant of 120±30 fs which is somewhat longer-lived (lifetime 670±80 fs), followed by the formation of a complex state (Cl:e^-), from which the solvated electrons are ejected with a time constant of 7±1.5 ps and large quantum yield.