1. Department of Material Science, Graduate School of Science, Osaka City University, Sugimoto, Sumiyoshi‐ku, Osaka 558‐8585, Japan, Fax: (internat.) + 81‐6‐6690‐2753
2. On leave from: Department of Chemistry, Guru Nanak Dev University, Amritsar 143005, India, Fax: (internat.) + 91‐183‐2‐258820