Subpicosecond relaxation of localized electrons in liquid ammonia

We report the results of an experimental study of the optical bleaching of the absorption spectrum of the solvated electron in dilute Na--NH3 and Na--ND3(2times10-4 M) solutions by a single 1.06 μ psec pulse (pulse duration 6 psec, pulse energy 30 mJ). The absorption spectrum of the solvated electron was monitored in the spectral range 1100--850 nm with the time resolution 20--3.3 psec. The line broadening of the solvated electron optical band originates from homogeneous broadening effects. The relaxation time of the excited state of the solvated electron was determined to be tauapprox. =2times10-13 sec. This ultrashort relaxation time favors relaxation between bound states of the solvated electron center