1. Research Center on Advanced Materials and Technologies, Sciences Department, “Alexandru Ioan Cuza” University of Iasi, 11, Boulevard Carol I, 700506 Iasi, Romania
2. Centre for Nanoscience and Nanotechnology, Centre National de la Recherche Scientifique - UMR 9001, Route de Nozay, 91400 Marcoussis, France
3. Institut Mines-Telecom, Telecom ParisTech, 46 rue Barrault, 75634 Paris Cedex 13, France