We observed vibrationally broadened emission bands for all solutions studied, which are characteristic for f-d transitions; the luminescence profile of 3-Eu is asymmetric and very broad, spanning most of the visible spectrum. Following excitation between 24,390-50,000 cm -1 (200-410 nm) for 1-Eu and 3-Eu the emission maxima occur in the green region (em = 18,020 cm -1 , 555 nm) of the electromagnetic spectrum and for 4-Eu and 4-Yb these are in the blue region (em = 21,050 cm -1 , 475 nm);