1. Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
2. Ebara Research Company, Ltd., 4-2-1 Honfujisawa, Fujisawa 251-8501, Japan
3. Department of Materials Technology, Chiba University, 1-33 Yayoicho, Inage-ku, Chiba 263-8522, Japan
4. Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Institute, 1233 Watanukimachi, Takasaki, Gunma 370-1292, Japan