1. CNR-NANOTEC Institute
of Nanotechnology, Via Monteroni, Lecce 73100, Italy
2. University of Salento, Department of Mathematics and Physics Ennio De Giorgi, Via Arnesano, Lecce 73100, Italy
3. CNR-IMM Institute
for Microelectronics and Microsystems, Strada VIII, Catania 95121, Italy
4. Molecular
Foundry,
Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States
5. CNR-NANOTEC
Institute
of Nanotechnology, Via P. Bucci, Rende 87036, Italy
6. University of Calabria, Department of Physics, Via P. Bucci, Rende 87036, Italy
7. Center for Nano Optics, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark