1. RIKEN SPring‐8 Center RIKEN, Sayo‐cho, Sayo‐gun Hyogo 679‐5198 Japan
2. School of Materials and Chemical TechnologyTokyo Institute of Technology Meguro‐ku Tokyo 152‐8552 Japan
3. Research and Development CenterZeon Corporation Kawasaki Kanagawa 210‐9507 Japan
4. Emeritus Professor of Tokyo Institute of Technology Meguro‐Ku Tokyo 152‐8552 Japan