In this work the fluorescence spectrum of Eu2+ doped CsCl single cryst
als has been systematically investigated for different annealing treat
ments. The quenched samples present an emission band peaking at 22700
cm(-1) due to Eu-vacancy complexes and two additional emissions at 220
40 and 20524 cm(-1). which ale related to small europium aggregates. T
hermal annealing of the samples induces the formation of Eu precipitat
es with a platelet-like structure along {220} crystal planes, giving r
ise to an emission band at 23120 cm(-1). A first result of an Eu2+ ind
uced aggregation by ultraviolet laser irradiation is presented.