1. Contribution from the Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan, Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region 142432 Russia, Institute of Solid-State Physics RAS, Chernogolovka, Moscow region, 142432, Russia, and Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan