1. Conducting Polymer Materials Group, Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA), 1233 Watanuki, Takasaki, Gunma 370-1292, Japan, Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 Japan, and Department of Electronic Engineering, Faculty of Engineering, Gunma University, 1-5-1 Tenjin, Kiryu, Gunma 376-8515, Japan