1. Department of Physics, University of Trieste, Trieste, Italy
2. Department of Physics, University of Perugia, Perugia, Italy
3. Institute of Physics Ecole Polytechnique Fédérale de Lausanne (EPFL) Station 3, Lausanne, Switzerland
4. MAX IV Laboratory, Lund, Sweden
5. CNR-IOM – Istituto Officina dei Materiali, Area Science Park, Trieste, Italy
6. Center for Energy, Environment and Transport Giacomo Ciamician, University of Trieste, Trieste, Italy