GROUND TERM L-QUANTUM AND J-QUANTUM NUMBER PROFILES OF THE OSCILLATOR-STRENGTHS (F(JO)) AND PH VALUES OF SOME LANTHANOIDS IN AMINOPOLYCARBOXYLATE LIGAND ENVIRONMENTS

Electronic spectral studies of some lanthanoids [(viz. Pr(III), Nd(III ), Sm(III), Eu(III), Dy(III), Er(III) and Tm(III)] in aminopolycarboxy late (viz. IMDA, NTA, HEDTA, EDTA, CDTA and DTPA) environment have bee n undertaken with a view to evaluate the oscillator strengths (f(JO)), Judd-Ofelt parameters (tau(lambda)), inter-electronic repulsion Racah parameters (partial derivative E(k)) and nephelauxetic ratios (partia l derivative E(3)/partial derivative E(1)). The parameters have been e valuated for the entire pH range (pH 2-9) with intervals of 0.5 in ord er to study the dependence of oscillator strengths on pH values. The e xtent of covalency (via parameter tau(2)) and symmetry (via parameters tau(4) and tau(6)) in the metal-ligand interaction have been estimate d with the help of tau(lambda) parameters. The values of oscillator st rengths and Judd-Ofelt parameters have been discussed in the light of coordination number of lanthanoid metal ions, denticity and basicity o f the ligands. The metal-ligand bonding pattern has been studied in th e light of changes in Racah parameters and the nephelauxetic ratio. Th e oscillator strength values for some specific hypersensitive transiti ons and for the transition where U-lambda values are significantly lar ge have been studied as a function of ground term L and J quantum numb ers of the lanthanoids.