Characterization of extraction complexes of Am(III) with dialkyldithiophosphinic acids by extended X-ray absorption fine structure spectroscopy

The structure of extraction complexes of Am(Ill) with di-n-octyldithiophosphinic acid and di(2,4,4-trimethylpentyl)dithiophosphinic acid in kerosene have been studied by extended X-ray absorption fine structure (EXAFS) spectroscopy. The EXAFS spectra demonstrate that the two extraction complexes are analogous in coordination structure with eight sulfur atoms coordinated in inner sphere. The coordination numbers and distances from the central Am atom to the nearest shell and the second shell atoms are: S, n=7.8+/-1, R=2.92 Angstrom; P, n=3.8+/-0.5, R=3.47 Angstrom for di-n-octyldithiophosphinic acid and S, n=7.8+/-1, R=21.98 Angstrom; P, n=3.7+/-0.4, R=3.58 Angstrom for di(2,4,4-trimethylpentyl) dithiophosphinic acid. (C) 2002 Elsevier Science B.V. All rights reserved.