1. Dipartimento
di Ingegneria E. Ferrari, Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena, Italy
2. Solid
State Physics Division, Ioffe Physical-Technical Institute of Russian Academy of Sciences, 26 Polytechnicheskaya str., 194021 St. Petersburg, Russia
3. Saint-Petersburg State Polytechnical University, 29 Polytechnicheskaya str., 195251 St. Petersburg, Russia
4. IOM-CNR, s.s. 14, Km. 163.5 in AREA Science
Park, 34149 Basovizza,
Trieste, Italy
5. Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin, BP 48, F-91192 Gif-sur-Yvette Cedex, France
6. Department
of Physics, University of Johannesburg, PO Box 524, Auckland Park 2006, South Africa