1. 1Department of Chemistry, Faculty of Education, Saga University, Honjo-machi 1, Saga 840, Japan
2. 2Department of Chemistry, Faculty of Science, Hiroshima University, Higashisenda-machi, Naka-ku, Hiroshima 730, Japan
3. 3Institut für Physikalische Chemie, Physikalische Chemie III, Technische Hochschule Darmstadt, Petersenstr. 20, D-6100 Darmstadt, Germany