1. Frontire Research Program, The Institute of Physical and Chemical Research (Riken), Hirosawa 2-1, Wako, Saitama 351-0198, Japan, Department of Material Chemistry, Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto 606-01, Japan, and Graduate School of Material Science, Nara Institute of Science and Technology (NAIST), Takayama-cho 8916-5, Ikoma, Nara 630-01, Japan