1. Instituto de Fisica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, C.P. 78000, San Luis Potosi, Mexico
2. Departamento de Química Física and Unidad Asociada CSIC, Universidade de Vigo, Campus Universitario, Vigo 3610, Spain
3. Institute of Condensed Matter and Nanosciences, Université Católica de Louvain, Place Croix du Sud 1 (PCPM, Boltzmann) 1348 Louvain La Neuve, Belgium, and Center for Nanophase Materials Sciences, Oak Ridge National Lab, One Bethel Valley Road, Oak Ridge, Tennessee 37831-6487, United States
4. Research Center for Exotic Nanocarbons (JST), Shinshu University, Wakasato 4-17-1, Nagano-city 380-8553, Japan