Femtochemistry of the Hydrated Electron at Decimolar Concentration

We report a femtosecond laser study of the transient absorption of hydrated electrons generated by 266 nm two-photon ionization of liquid water under very high power laser density (up to 1.5 TW/cm²). The two-photon absorption coefficient of liquid water for femtosecond pulses at 266 nm was determined to be β = (1.8 ± 0.4) × 10^-11m/W. The quantum yield of formation of the hydrated electron per absorbed photon at 266 nm is determined to be 0.26 ± 0.02. We observed, for the first time, that the decay of the hydrated electron produced under 1.5 TW/cm² laser pump power density in pure water is not only due to geminate recombination and that the survival probability of the hydrated electron at 1 ns is 0.16 ± 0.02 under those conditions, where an unprecedented local concentration of the hydrated electron of 0.15 M is produced.