1. Instituto de Física, Universidade Federal de Uberlândia, 38400-902, Uberlândia, MG, Brazil
2. Ilum School of Science, Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, 13083-970, Brazil
3. Brazilian Nanotechnology National Laboratory, Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, 13083-970, Brazil
4. Universidade Federal do ABC (UFABC), 09210-580 Santo André, São Paulo, Brazil