LUMINESCENCE STUDY ON DETERMINATION OF THE HYDRATION NUMBER OF CM(III)

A luminescence study of Cm(III) has shown a linear correlation between the decay constant k(obs) (the reciprocal of the excited-state lifetime) and the number of water molecules n(H2O) in the first coordination sphere of complexes. From measurements of k(obs) of Cm3+ in D2O-H2O solutions and of Cm(III) doped lanthanum compounds, the following correlation for k(obs) (ms(-1)) vs. n(H2O) was established: n(H2O) = 0.65k(obs) - 0.88. This relationship was applied to study of the residual hydration of Cm(III) complexes of polyaminopolycarboxylate ligands. The hydration number of Cm(III) in these complexes is apparently larger than that of Eu(III).