1. División de Ciencias e Ingenierías, Campus León, Universidad de Guanajuato, León, Gto. 37150, México
2. Optical Technology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
3. Department of Chemistry, Winston-Salem State University, Winston-Salem, North Carolina 27110, United States
4. Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States