1. Department of Physics, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland
2. Departamento de Química, Universidad de Guadalajara, CUCEI, Blvd. Marcelino García Barragán 1421, C. P. 44430 Guadalajara, Jalisco, Mexico
3. Department of Chemistry, Nanoscience Center, University of Jyväskylä, FI-40014 Jyväskylä, Finland