| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Shinji Okazaki National Research Institutes, Institute for Molecular Science, Assistant, 分子科学研究所, 助手 (10228447)
MANIWA Yutaka Tokyo Metropolitan University, Graduate School of Science, Associate Professor, 大学院・理学研究科, 助教授 (70173937)
KENJI Ichimura Kumamoto University, Graduate School of Natural Science and Technology, Professor, 大学院・自然科学研究科, 教授 (00151481)
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| Research Abstract |
(1)Preparation and characterization of C_<60>-rare gas compounds
The samples were prepared by exposure to C_<60> powders at 473 K in 1 atm rare gas (RG) for several days. From mass-analyzed thermal desorption measurements, RG in C_<60>-He, C_<60>-Ne and C_<60>-Ar was desorbed at high temperature of 500-700 K. From XPS measurements, Ar2p and Ar3s bands were detected in C_<60>-Ar and they showed large chemical shifts. From ESR measurements, weak signals were observed in C_<60>-He and C_<60>-Ar. These results mean that RG occluded in the C_<60> lattice has a chemical interaction with C_<60>.
(2)Theoretical calculation of C_<60>-rare gas compounds
In order to quantitatively evaluate the interaction between RG and C_<60>, we performed the electronic state calculation of C_<60>(RG)~ (n=1,2,3) crystals. It was found that the charge transfer occurs between RG and C_<60>. RG in C_<60>(RG) (RG=He,Ne,Ar) are neutral, Whereas those in C_<60>Kr and C_<60>Xe have positive Mulliken charges of 0.99 and 1.04, respectively. For C_<60>(RG)_2 and C_<60>(RG)_3, a slightly positive charge of 0.02 appeared on Ar atom in C_<60>Ar_2 and C_<60>Ar_3.
(3)Rare gas occlusion in carbon nanotubes
We investigated the interaction between RG and carbon nanotubes (CNT) using four kinds of CNT by combination of multi-wall/single-wall and closed endcaps/opened endcaps. For CNTs exposed to He, Ne and Ar, the desorption peak was observed at high temperature, which means the presence of the chemical interaction. The closed endcaps CNTs occluded larger amount of gas than the opened endcaps CNTs. It is concluded that as the interactive site, the endcaps and related sites are more important than the inside of tube.
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