ABSORPTION AND EMISSION SPECTROSCOPIC PARAMETERS OF ND-3+ AND EU-3+ IONS IN THEIR HEXAMETHYLPHOSPHORAMIDE COMPLEXES

Syntheses of the following complexes are reported: LnX3.6L, LnX'3.4L, LnX"3.3L and Eu(NCS)3.3L, where Ln = Nd3+, Eu3+; L = hexamethylphosphoramide (hmpa); X = ClO4-, PF6-; X' = NCS-, NO3-, Br-, ClO4-; X" = Cl-. Spectra of the complexes of Nd3+ (absorption) and Eu3+ (emission) in dichloromethane solutions were measured. The oscillator strengths of the Nd3+ f-f absorption bands within the 11 000-30 000 cm-1 region were determined and the tau-lambda intensity parameters were obtained according to the Judd-Ofelt formalism. Covalency parameters were also determined for the Nd3+ complexes. The intensities relationship eta-21 of the 5D0 --> 7F2 and 5D0 --> 7F1 transitions of the Eu3+ was calculated. A good correlation between tau2 and the oscillator strength of the hypersensitive band of Nd3+ was found, as well as a correlation between tau-2 and eta-21. There are only qualitative relations between tau-2 and the covalency parameter.