1. Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, S-221 00 Lund, Sweden, DISTAM, Università del Molise, v. De Santis, I-861 00 Campobasso, Italy, Condensed Matter Physics and Chemistry Department, Risø National Laboratory, DK-4000 Roskilde, Denmark, and Dipartimento di Chimica, Università di Bari, v. Orabona 4, I-70126 Bari, Italy