1. Group of Nanoscience and Nanotechnology, Physics Department, Federal University of Juiz de Fora (UFJF), Juiz de Fora, Minas Gerais 36036-900, Brazil
2. Materials Metrology Division, National Institute of Metrology, Quality, and Technology (INMETRO), Duque de Caxias, Rio de Janeiro 25250-020, Brazil