1. Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, Texas 76109-0065, United States
2. Department of Physics, The University of Texas at Arlington, Arlington, Texas 76109-0065, United States
3. Department of Applied Physics, CINVESTAV, Merida, Yucatan 97310, Mexico
4. Department of Physical, Chemical and Natural Systems, Universidad Pablo de Olavide, Seville 41013, Spain