1. Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48, Vassileos Constantinou Ave., Athens 116-35, Greece
2. Organic Chemistry Institute, National Hellenic Research Foundation, Athens 116-35, Greece
3. Institute of Materials Science, NCSR, Demokritos, Athens 153-10, Greece
4. Institute of Microelectronics, NCSR, Demokritos, Athens 153-10, Greece
5. Graduate School of Science, Osaka City University, Osaka 558-8585, Japan