1. REQUIMTE/CQFB, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal, Nanomaterials Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-1349, Department of Chemistry, University of Georgia, Athens, Georgia 30602-2556, and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, U.K.