Study of sensitized luminescence of rare earths. Fluorescence enhancement of the europium—terbium (or lutetium)—β-diketone—synergistic agent complex system and its application

Abstract

Study of the enhancement effect on the fluorescence intensities of the Eu 3+ -thenoyltrifluoroacetone(TTA)-cetyltrimethylammonium bromide (CMAB) system by Tb 3+ and of the Eu 3+ -dibenzoylmethane(DBM)—diethylamine(DEA) system by Lu 3+ has been carried out in a colloidal suspension. In the presence of terbium or lutetium the fluorescence intensities of the above systems were enhanced by a factor of about 100 at a pH from 5.5 to 8.0 and 9.5 to 11.5, respectively. The excitation wavelength was 372nm for the Eu-TTA-CTMAB system and 390nm for Eu-DBM-DEA system. The emission wavelength was 612 nm. Fluorescence intensity was a linear function of the concentration of europium in the range 1.0 × 10 −12 -1.0 × 10 −8 mol dm −3 for the Eu-TTA-CTMAB system and 5.0 × 10 −11 -1.0 × 10 −7 mol dm −3 for the Eu-DBM-DEA system, respectively. The detection limit was 1.0 × 10 −13 mol dm −3 for the Eu-TTA-CTMAB system and 5.0 × 10 −12 mol dm −3 for the Eu-DBM-DEA system. The standard addition method was used for the determination of europium in rare earth oxides and gave satisfactory results.