1. Department of Physics, "Alexandru Ioan Cuza" University of Iasi, Blvd. Carol I, no. 11, 700506, Iasi, Romania
2. National Institute of R&D for Technical Physics-IFT Iasi, Blvd. D. Mangeron, no. 47, 700050, Iasi, Romania
3. Petru Poni Institute of Macromolecular Chemistry, 41A, Gr. Ghica Voda Alley, 700487, Iasi, Romania