1. Laboratory for Nanoscience and Nanotechnology Research (LINAN) and Advanced Materials Department, IPICyT. Camino a la Presa Sn. Jose 2055, San Luis Potosí, Mexico, 78216
2. Oak Ridge National Laboratory, P.O. Box 2008, MS6367, Oak Ridge, Tennessee 37831-6367
3. Université Catholique de Louvain, PCPM & ETSF, Place Croix du Sud 1, B-1348 Louvain-la-Neuve, Belgium