1. Department of Physical and Chemical Sciences, University of L'Aquila, Via Vetoio, 67100 L'Aquila, AQ, Italy
2. College of Science, Institute of Materials Physics and Chemistry, Nanjing Forestry University, Nanjing 210037, P. R. China
3. Sensor Lab, Department of Information Engineering, University of Brescia, Via Valotti 9, 25133 Brescia, Italy
4. Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Prague 8, 18000 Prague, Czech Republic
5. Elettra – Sincrotrone Trieste SCpA, AREA Science Park, Strada Statale 14 km 163.5, 34149, Trieste, Italy
6. National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
7. Department of Physics, National Cheng Kung University, 1 Ta-Hsueh Road, 70101 Tainan, Taiwan