Absorption and Fluorescence Spectra of Several Praseodymium-Doped Crystals and the Change of Covalence in the Chemical Bonds of the Praseodymium Ion

Abstract

The absorption and fluorescence spectra of praseodymium-doped lanthanum trifluoride, lanthanum ethylsulfate, and yttrium aluminum garnet single crystals are reported. The center of gravity of each J level is shifted to the red when the nearest neighbors of the praseodymium ion change in the order of fluorine, water, chlorine, bromine, and oxygen. This corresponds to an increase of covalent character by 0.7, 0.9, 1.1, and 2.0% for Pr–H2O, Pr–Cl, Pr–Br, and Pr–O bonds when compared with Pr–F.