HYDRATED ELECTRON GENERATION BY MULTIPHOT ON ABSORPTION OF 2 EV FEMTOSECOND LASER-PULSES

A promptly formed species (< 1 ps) is produced in large quantity (appr oximately 10(-3) M) when pure water is submitted to very short (approx imately 150 fs) and very intense (approximately 0.5 mJ) 2-eV laser pul ses. Its absorption spectrum identifies the species as the hydrated el ectron, e(aq)-. An investigation of the e(aq)-, production rate versus pulse intensity suggests that the presence of the A B-1(1) electronic state' of liquid H2O at 8.4 eV assists the multiphoton ionization pro cess. Furthermore, a stimulated Raman gain is observed at 780 nm along with the inverse Raman effect on the anti-Stokes side at 512 nm. The recorded isotopic shift of the involved vibrational level with D2O con firms this latter interpretation.