Small-polaron approach to the hydrated electron: semiclassical model

Application of the small-polaron theory of Emin and Reik to the hydrated electron gives the physical meaning of the electron transfer (ET) transitions to the main band of the absorption spectrum, in contrast to the more popular interpretation as the electronic 1s → 2p transition. A semiclassical orientational polarization model for the hydrated electron shows that the ET transition and the 1s → 2p transition have excitation energies of about the same magnitude at the absorption peak, despite the difference in the physical meaning, but the line width of the ET transition is larger than that of the 1s → 2p transition. The configuration interaction of these two modes of excitation generates an additional weak uv transition, which resembles the interband transition of small polarons