Cooperative Vibronic Spectra.

This work is divided into two parts. In the first part the basic theory of energy transfer processes and cooperative optical phenomena are developed for a transparent host doped both with trivalent rare earth ions and OH(' -) ions. The stretching motions of the latter are considered to be like those of OH('-) impurities in alkali halides. Calculations of transition probabilities are made for several specific cases. In the second part spectroscopic results and a detailed theoretical treatment are presented for cooperative optical transitions involving Tb('3+) ions and water molecules in polycrystalline hydrates and aqueous solutions. The positions, widths, intensities, and selection rules of the observed cooperative vibronic bands are well explained by the theory.