PHOTOLUMINESCENCE PROPERTIES AND CRYSTAL-STRUCTURE OF K3NA4H2TBW10O36.20H2O

The photoluminescence properties of the potassium sodium salt of decatungstoterbate, K3Na4H2TbW10O36.20H2O, are studied and compared with those of its sodium salt. Photoexcitation of the ligand-to-metal (oxygen-to-tungsten) charge transfer (O --> W LMCT) band of the W5O18 groups in this complex leads to green emission due to the f --> f transition within terbium(III), as a result of an intramolecular energy transfer from the W5O18 groups to terbium(III). The quantum yields of the O --> W LMCT excitation are comparable between the two salts, while the quantum yield of the direct excitation of terbium(III) in the potassium sodium salt is about three times greater than that in the sodium salt.