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Yaita, Tsuyoshi; Shiwaku, Hideaki; Suzuki, Shinichi; Okamoto, Yoshihiro; Shimada, Asako*; Assefa, Z.*; Haire, R. G.*
Physica Scripta, T115, p.302 - 305, 2005/00
The structural parameter and the electronic structure of the complex between cerium and N,N'-dimethyl-N,N'-diphenylpyridine-2,6-carboxyamide(DMDPhPDA) was investigated by XAFS, photo luminescence and excitation spectra. The DMDPhPDA is one of the promising ligands for separation of trivalent actinides from lanthanides. The Ce-K XAFS spectra were measured at BL11XU of SPring-8. The bond distances between the carbonyl oxygens and cerium, and between the pyridyl nitrogen and cerium are 253pm and 264pm, respectively. The bond angle of the plane consisting of the two carbonyl oxygens and nitrogen with cerium was about 180 degree. This complex was a yellow color unique for the DMDPhPDA-lanthanide complexes. The photo absorption peak for the complex was extremely broad, and the peak position was at a higher wavenumber as compared with those for the other lanthanide complexes. The peak in the highest wavenumber of this band may be attributed to the transition between f and d orbitals, which are greatly influenced by the ligand field of the DMDPhPDA. The XANES spectrum of the cerium complex clearly showed that cerium was trivalent.
Assefa, Z.*; Yaita, Tsuyoshi; Haire, R. G.*; Tachimori, Shoichi
Inorganic Chemistry, 42(23), p.7375 - 7377, 2003/11
Times Cited Count：11 Percentile：36.69(Chemistry, Inorganic & Nuclear)The 6-methyl- 2-(2-pyridyl)-benzimidazole (biz) ligand coordinates with the actinide species in solution, and the complexes display efficient intra-molecular energy-transfer processes. The energy transfer in the Cm(III):biz system proceeds in a non-radiative mode, whereas a radiative mode is the principal mechanism in the Am(III)-biz system.
Hayashi, Hirokazu; Akabori, Mitsuo; Minato, Kazuo; Haire, R. G.*
no journal, ,
The electrochemical behavior of Am at a liquid Cd cathode and the alloying behavior of Am with Cd were analyzed. In the cyclic voltammograms obtained with Mo electrode, the redox reactions of Am(III)/Am(II) and Am(II)/Am were observed, while peaks assigned to Am(III)/Am (in Cd) were observed with liquid Cd electrode. The observed electric potentials for the peaks with liquid Cd electrode were more positive than those with Mo electrode. The difference in the potentials 
E(Am-Cd) was 0.39V, which is similar to E(Pu-Cd) and much larger than E(U-Cd) and E(Np-Cd). It is reported that E(An-Cd) (An=U, Np, Pu) corresponds to G
of An-Cd compound formed at Cd electrode (UCd
, NpCd
, PuCd). On the other hand, to identify the stable chemical form on Am-Cd phase diagram, Am-Cd intermetallic compounds were prepared by heating 
Am metal with liquid Cd. The product prepared by heating at 723K was identified as cubic AmCd
with a
=1.559 
0.002 nm by powder X-ray diffraction. AmCd is considered to be formed at Cd electrode on the electrochemical experiments because it is the stable product at 723K.
