1. Applied Physics Department, Jerusalem, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
2. Department of Chemical Sciences, University of Padova, Via Marzolo 1, I-35131 Padova, Italy
3. Nancy and Stephen Grand Technion Energy Program, Russell Berrie Nanotechnology Institute, Quantum Information Center, Schulich Faculty of Chemistry, Solid State Institute, Technion Israel Institute of Technology, Solid Stat, IL-3200003 Haifa, Israel
4. The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
5. The Center for Nanoscience and Nanotechnology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel