Excited-state photoionization of Ce3+ ions in Ce3+:CaF2.

摘要: The formation of stable color centers in Ce/sup 3+/:CaF/sub 2/ is found to result from the optical pumping lowest 4f..-->..5d absorption band 3+/ ions at C/sub 4//sub v/ symmetry sites with a 308-nm excimer laser. Absorption spectra these indicate that they are 2+/ located having O/sub h/ symmetry. photochromic since can be optically bleached. Measurements dependence number on incident laser intensity and length exposure presented. data interpreted terms two-step photoionization subsequent electron capture ion Rate equations incorporating two-photon creation term one-photon bleaching formulated their solutions consistent observed color-center growth kinetics. implications this work for other potential vibronic materials also discussed.