1. Dipartimento
di Chimica, Università degli Studi di Milano, Via C. Golgi
19, I-20133 Milano, Italy
2. ISTM-CNR and INSTM Unit, Via C.
Golgi 19, I-20133 Milano, Italy
3. Institut Laue-Langevin, BP 146, 38042 Grenoble Cedex 9, France
4. European Synchrotron Radiation Facility, 6 av. J. Horowitz, BP 220, 38043 Grenoble Cedex, France