Absorption spectrum of the hydrated electron paired with nonreactive metal cations

We studied the effects of eight chloride and five perchlorate salts of monovalent, divalent or trivalent metal cations at high concentration in water on the optical absorption spectrum of the hydrated electron. Whatever the salt, the maximum of the hydrated electron absorption spectrum shifts toward shorter wavelength (“blue shift”) as the salt concentration is increased. The effects of the salt concentration, cation charge and counterion on the blue shift are discussed.