1. Department of Physics, University of Calabria, Ponte P. Bucci, Cubo 33B, 87036 Rende Cosenza, Italy
2. CNR-Nanotec c/o Department of Physics, University of Calabria, Ponte P. Bucci, Cubo 33B, 87036 Rende Cosenza, Italy
3. Department of Chemistry and Biochemistry, University of Tulsa, 600 S. College Ave., Tulsa, OK 74104, USA
4. Gilcrease Museum, 1400 N Gilcrease Museum Rd., Tulsa, OK 74127, USA