1. School of Nano & Advanced Materials Engineering, Changwon National University, 9 Sarim Dong, Changwon 641-773, Republic of Korea
2. Nano Analysis Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
3. Instituto de Fisica Gleb Wataghin, Universidade Estadual de Campinas, (UNICAMP) Campinas, 13.083-859, SP, Brazil