Photoluminescence of europium (3) polymolybdate complexes

The sensitized photoluminescence of Eu(3) at room temperature in the acidified solutions (pH 3.5-5.5) of sodium molybdate and ammonium paramolybdate is studied. The sensitization is due to the energy transfer on Eu(3) inside europiummolybdate heteropolycomplex. Crystalline europium polymolybdate is obtained from molybdic solutions and its composition is (NH4)28Eu8Mo58xnH2O. This crystal possesses the bright red luminescence whose lifetime varies from 220 to 260 μs for different species. The analysis of luminescence spectra allows one to make a conclusion that the site symmetry for Eu3+ in crystals approaches C2 or Cs. The luminescent method for determining europium with the aid of molybdic solutions is proposed. The quenching action of luminescence by other lanthanide ions id insignificant. The absence of luminescence of terbium (3) and curium (3) polymolybdate complexes is discussed