1. Department of Chemistry, Faculty of Science, Kobe University, Nada, Kobe 657-8501, Japan, Hyogo University of Teacher Education, Shimokume, Yashiro-cho, Kato-gun, Hyogo 673-14, Japan, and Laboratoire d'Electrochimie Physique et Analytique, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland