Unusual optical emission from microcrystals containing Eu2+: Experiment

Experimental observations and inferred properties are reported for an optical emission near 368 nm which is unusual in that it occurs selectively from microcrystals of optical wavelength dimensions and is anomalously fast and efficient. The properties of principal interest are: (i) the emission exhibits a large quantum efficiency (>0.1) in microcrystals of optical wavelength dimensions, but becomes unobservable in crystals with significantly …