Competitive Excitation Mechanisms for the Blue Fluorescence in CdF2:1%Er3+

Abstract

We report direct experimental evidence of the coexistence of two distinct optical double-resonance processes resulting in the blue (0.41-μ) fluorescence in Cd${\mathrm{F}}_2$:1%${\mathrm{Er}}^{3+}$. Our experiments contradict the conclusions of Feofilov and Ovsyankin who claim that the cooperative process properly describes long-wavelength activated visible fluorescence.