1. Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura Nishikyo-ku, Kyoto 615-8510, Japan
2. Department of Applied Chemistry, School of Engineering, Kyushu University, Motooka, Fukuoka 812-0053, Japan
3. HVEM Laboratory at Center for Advanced Research of Energy and Materials, Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
4. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Ibaraki 319-1106, Japan