The first example of fluorescence of the solid individual compounds of Eu ion: EuCl , EuI , EuBr.

Fluorescence (FL) from Eu ion solid individual compounds was observed for the first time using the examples EuCl , EuI and EuBr . Fluorescence was detected at excitation by ultraviolet (UV) light from powdered samples of Eu (II) halides at room temperature (RT) in an argon atmosphere. In air, FL of all Eu compounds studied was stable, and intensity persisted for weeks. Depending on the nature of the halide anion and due to a nephelauxetic effect, the position of the maxima in the FL spectra underwent a red shift in the series: EuCl (409 nm) < EuBr (428 mm) < EuI (432 nm). The lifetimes of the excited states of the Eu * ions for EuI , EuCl and EuBr were 355, 76 and 54 ns, respectively.