1. Department of Physics, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan, and Department of Chemistry, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Kyoto 606-8502, Japan