1. Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48, Vassileos Constantinou Ave., Athens 116-35, Greece
2. Institute of Chemical Engineering and High Temperature Chemical Processes (ICE-HT), Foundation for Research and Technology-Hellas (FORTH), Patras 265-04, Greece and Department of Physics, University of Patras, Patras 265-04, Greece
3. Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan