Kyoto University

About: Kyoto University is a education organization based out in Kyoto, Japan. It is known for research contribution in the topics: Population & Catalysis. The organization has 85837 authors who have published 217215 publications receiving 6526826 citations. The organization is also known as: Kyōto University & Kyōto daigaku.

Compositional dependence of Judd-Ofelt parameters of Er3+ ions in alkali-metal borate glasses.

Abstract: The Judd-Ofelt intensity parameters, ${\mathrm{\ensuremath{\Omega}}}_{\mathit{t}}$ (t=2,4,6) for f-f transitions of ${\mathrm{Er}}^{3+}$ ions doped in ${\mathrm{B}}_{2}$${\mathrm{O}}_{3}$-${\mathit{R}}_{2}$O (R=Na,K) glasses were determined from optical-absorption measurements, and their compositional dependence was investigated systematically. The values of ${\mathrm{\ensuremath{\Omega}}}_{2}$ exhibited a maximum around 25 mol % ${\mathit{R}}_{2}$O, while those of ${\mathrm{\ensuremath{\Omega}}}_{4}$ and ${\mathrm{\ensuremath{\Omega}}}_{6}$ decreased monotonically with an increase in ${\mathit{R}}_{2}$O content. The compositional dependences of ${\mathrm{\ensuremath{\Omega}}}_{4,6}$ were consistent with those of the isomer shift in $^{151}\mathrm{Eu}$ M\"ossbauer spectroscopy, which gives information about the 6s-electron density of ${\mathrm{Eu}}^{3+}$ ions. The variation of ${\mathrm{\ensuremath{\Omega}}}_{2}$ against ${\mathit{R}}_{2}$O content was related to the change in asymmetry of the rare-earth ligand due to the structural mixing of borate groups, while those of ${\mathrm{\ensuremath{\Omega}}}_{4,6}$ were related to the local basicity of rare-earth sites in the glass.

Encapsulation of Molecular Hydrogen in Fullerene C60 by Organic Synthesis

Abstract: In spite of their importance in fundamental and applied studies, the preparation of endohedral fullerenes has relied on difficult-to-control physical methods. We report a four-step organic reaction that completely closes a 13-membered ring orifice of an open-cage fullerene. This process can be used to synthesize a fullerene C60 encapsulating molecular hydrogen, which can be isolated as a pure product. This molecular surgical method should make possible the preparation of a series of C60 fullerenes, encapsulating either small atoms or molecules, that are not accessible by conventional physical methods.