1. Departments of Materials Science and of Chemistry, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan, The Institute for Solid State Physics, The University of Tokyo, Minato-ku, Tokyo 106-8666, Japan, and Department of Pure and Applied Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo 153-8902, Japan