1. Department of Energy and Hydrogencarbon Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, 615-8510, Japan
2. Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
3. Department of Physics, Columbia University, New York, New York 10027
4. TRIUMF, Vancouver, British Columbia, Canada V6T 2A3
5. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada L8S 4M1
6. Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan
7. Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan