1. IMEM-CNR-FBK Division of Trento, Via alla Cascata 56/C, I-38123 Povo, Italy
2. Nanoscience Laboratory, Department
of Physics, University of Trento, Via Sommarive
14, I-38123 Povo Trento, Italy
3. CNR-SPIN and Department of Physics
Science, University of Naples “Federico II”, P.le Tecchio 80, 80125, Naples, Italy
4. Department of Chemistry, University of Naples “Federico II”, Via
Cinthia, I-80126 Naples, Italy
5. Research Laboratory for Surface
Science, Okayama University, Okayama 700-8530,
Japan