The Flourescence of Rare Earth Ions in Alkali Halides

Abstract

High resolution fluorescence spectra are presented of the sideband of the 5D0+ 7F0 transition of Sm++ in KBr and KCl. Several Van Hove singularities of the phonon spectrum of the host material are directly observed. They occur at slightly different frequenciesfromthose predicted by density of states calculations based on neutron diffraction measurements. Numerical calculations of both sidebands are given and compared with experiment, with quite good agreement. Sidebands observed for Eu++ in KBr and KCl are also presented and discussed.