1. Department of Chemistry, Tokyo Institute of Technology, Ohokayama, Meguro, Tokyo 152, Japan
2. Department of Chemistry, Tokyo Metropolitan University, Minami-Ohsawa, Hachioji, Tokyo 159-03, Japan
3. The National Institute for Environmental Studies, Tsukuba, Ibaraki 305, Japan
4. Department of Material Science, Himeji Institute of Technology, Kamigori, Hyogo 678-12, Japan