We traced the synthesis process of water-soluble metallofullerenols using radioactivity. The synthesized yield of 153Sm@C82(OH)n from 153Sm@C82 was determined to be about 60%, but 26% of 153Sm were adsorbed in size-exclusion gel chromatography column. The recovery yields of activated Sm@C82(OH)n in nuclear reactor are 5–15% when using Sm@C82(OH)n as irradiation materials, and they are up to 65–88% when using Sm@C82(OH)n mixed with a quantity of C60(OH)m. It was found that the effective synthesis process for a radio-metallofullerenol is the neutron irradiation of metallofullerenol
mixed with C60(OH)m.
Authors:K. Sueki, K. Akiyama, K. Kikuchi, H. Nakahara, and K. Tomura
The effect of β−-decay on the stability of metallofullerenes was investigated for three decay chains of155Sm-155Eu,161Gd-161Tb and177Yb-177Lu. For the former two cases, the metallofullerenes were found stable even after the β−-decay while in the case of177Yb, the metallofullerene became unstable after β−-decay. The present results point to the fact that metallofullerenes are stable against ordinary β−-decay unstable after β−-decay. The present results point to the fact that metallofullerenes are stable against ordinary β−-decay recoil energies, but they become unstable if the oxidation state of the metal atom is changed by nuclear transformation.
Authors:K. Masumoto, T. Ohtsuki, K. Sueki, K. Kikuchi, and T. Mitsugashira
The11C and14C labeled fullerenes were produced by charged-particle and neutron irradiation, of C60, C70 and their mixture. It was found that a carbon atom of fullerence can be easily exchanged with a radioactive carbon atom produced
by a nuclear reaction. The HPLC method was effective for identification and purification of various labeled fullerene families
as chemically stable compounds. The radiochemically interesting aspect of the results is not only the production of11C and14C labeled fullerenes but also the formation of radioactive higher fullerenes which can be simultaneously produced with high
yield and in carrier-free form.
Authors:T. Ohtsuki, K. Masumoto, K. Sueki, K. Shikano, and T. Shigematsu
Fullerenes, C60 and C70, were irradiated by 8 and 10 MeV deuterons. The irradiated samples were dissolved in CS2 and filtered to remove insoluble by-products. Finally, radioactive fullerenes and products, such as fullerene dimers, trimers
labeled with13N, were isolated and detected in the liquid phase by radiochromatography. This suggests that the energy rich13N atoms successfully incorporated into the fullerene cages and that the disrupted cages reacted with neighboring cages.
Authors:K. Sueki, K. Kikuchi, K. Tomura, and H. Nakahara
The stability of 16 kinds of metallofullerenes (9 elements) was investigated against the recoil phenomena associated with
the capture of neutrons by the metal atoms inside the carbon cages. The yields of the unaffected species were obtained by
use of the HPLC separation method and radioactivity measurements. Recoil energy distributions of the metal atoms were calculated
theoretically and the effective energy required for destruction of metallofullerenes from inside by recoiling atoms was estimated
to be about 10 to 15 eV for the metallofullerenes containing lanthanide atoms.
Authors:H. Nakahara, K. Sueki, W. Sato, and K. Akiyama
Radiochemical techniques have been applied in various ways to the study of fullerenes and metallofullerenes for the past several years, and they have provided invaluable information pertaining to the stability, structures, and formation of the novel carbon material. This paper reviews those experimental results that have fully shown the usefulness and uniqueness of radionuclides demonstrated in the field of fullerene science.
Authors:K. Sueki, Y. Oura, W. Sato, H. Nakahara, and T. Tomizawa
Nondestructive determination of major and trace elements within voluminous materials has been demonstrated by prompt γ-ray
neutron activation analysis. Some fragmented pieces of pottery bowls considered to have been produced in the late 18th century
were analyzed by a new internal monostandard method, and noticeable differences of the elemental contents and significant
correlations of the elemental distributions were observed among the samples. The possibility of identification of producing
areas of unearthened material is demonstrated by the analytical results and the applicability of this method to the investigation
of precious samples in a completely nondestructive way is verified in practice.
Authors:K. Akiyama, H. Haba, K. Tsukada, M. Asai, A. Toyoshima, K. Sueki, Y. Nagame, and M. Katada
The properties of a metallofullerene that encapsulates 225Ac were studied by radio-chromatographic methods. The results of chromatography on a Buckyclutcher column suggest that there
are some metallofullerene isomers of AcC82. The identical HPLC retention time of the major AcC82 peak with that of La@C82 indicates that the structure of one of the AcC82 isomers is the same as La@C82.
Authors:K. Sueki, K. Akiyama, Y. Zhao, I. Ito, Y. Ohkubo, K. Kikuchi, M. Katada, and H. Nakahara
We made systematic studies of lanthanoid metallofullerenes on the following three properties using the radiochemical method: (1) the relative production yields of metallofullerene species, (2) variation of the HPLC retention time among M(III)@C82 species, and (3) the effects of the reactor irradiation on the survival yields of each metallofullerene species. The production yields of M@C82 relative to La@C82 were found to decrease as the atomic number of M became larger and as the number of atom ratio, M/C, in the carbon rod became larger. On the other hand, the production yields of M1M2@C82, relative to that of LuM@C82 were found to increase for the larger atomic number. The retention time for the M(III)@C82 species in the Buckyprep column was found to become slightly longer for the larger atomic number but it becomes abruptly larger for Gd, and Tb by about 5%. The overall effects of the reactor irradiation on the survival yields (or retention yields) of M@C82 species were found to be (19.7±2.1)%.
Authors:Y. Zhao, I. Nishinaka, Y. Nagame, K. Tsukada, K. Sueki, S. Goto, M. Tanikawa, and H. Nakahara
The primary fragment mass-yield distribution for the asymmetric fission path in heavy nuclei, 233Pa, 239Np, 245Am and 249Bk at the excitation energy of ~20 MeV are experimentally constructed based on the intensities of total kinetic energies for individual mass splits. The results revealed an interesting phenomenon: in all the studied fissioning systems, the inner wings of the mass-yield distributions in the asymmetric fission path appear along the same mass-wall of A = 130 fragment mass. The asymmetric mass-yield distribution indicates the strong effect of structural shells in fragments on the final mass division process of the asymmetric fission path.