1. Department
of Physics and Chemistry, Faculty of Pharmaceutical Sciences at Ribeirão
Preto, University of São Paulo, Ribeirão Preto, SP 14040-903, Brazil
2. Department
of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
3. Centre
for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo, Norway
4. Department
of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo, Norway