1. Institute of Chemistry University of Campinas - UNICAMP P.O. Box 6154 13083-970 Campinas SP Brazil
2. Present address: Department of Engineering Federal University of Lavras, P.O. Box. 3037 37200-900 Lavras MG Brazil
3. Brazilian Synchrotron Light Laboratory - LNLS P.O. Box 6192 13087-500 Campinas SP Brazil
4. Present address: Brazilian Nanotechnology National Laboratory (LNNano) Brazilian Center for Research in Energy and Materials (CNPEM) 13083-100 Campinas SP Brazil
5. Department of Chemical Engineering Federal University of São Carlos P.O. Box 676 13565-905 São Carlos SP Brazil