Delocalizing electrons in water with light

Experimental information on the spatial extent of the putative p and conduc tion band states of the hydrated electron (e(eq)) has been obtained by moni toring and controlling the electron/hole spatial separation of a photogener ated eq/hole pair using a femtosecond laser pulse sequence. Optical excitat ion of e(eq) with two photons is observed to dramatically alter its spatial distribution and geminate recombination yield with the hole. One-photon ex citation, in contrast, has no effect on the spatial distribution. The resul ts strongly confirm theoretical predictions on the size and location of exc ited states of e(eq).