Application of the oscillator strength of 'hypersensitive' transitions to the investigation of complex equilibria of lanthanide ions

A method of evaluation of stability constants for the lanthanide complexes from the changes of oscillator strengths of 'hypersensitive' f-f transitions as a function of total ligand concentration is proposed. The method is discussed for neodymium acetate and glycolate and holmium lactate complexes. Stability constants calculated for mononuclear species are compared with the potentiometric data of Sonesson. This method is also useful for the calculation of thermodynamic parameters using measurements of the oscillator strength on temperature. The method is limited to lanthanide ions with f2-f6 and f8-f12 electronic configurations. (author)