A modified method for the evaluation of spectral parameters of 4f→ 4ftransitions in 'Pr(III) and Nd(III) complexes

267-269A modified method has been proposed for evaluating the energy interaction, spin-orbit interaction, bonding, nephelauxetic, oscillator strength and Judd-Ofelt parameters for Pr3+ and Nd3+ = systems. The parameters have been evaluated using an HP-1000/45 computer and by assuming certain boundary conditions. By this method, the root mean square (rms)values for the energies are reduced to the order of -20-50 cm-1 as compared to the values ~ 200-250 cm-1 obtained by earlier workers. For Pr(III) complexes, two correction parameters T7; (positive correction) and T8 (negative correction) are introduced which bring down the rms values in oscillator strength and Tλ parameters and also reduce the negative values observed for T2 parameter. A new hypersensitive band 4I9/2 → 4F5/2 is observed apart from the usual hypersensitive 4I9/2 → 4G5/2 band in the case of Nd(III)-nucleoside/nucleotide systems and this has been also taken into consideration in the evaluation of parameters. A new correction parameter Tc is used in explaining the spectral data of Nd(III); it makes the interpretation of spectral data in solution more meaningful. This method has been tested for the spectra of ~ 200 complexes of Pr3+ and an equal number of Nd3+ complexes