1. Nanotechnology
and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
2. Center
for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87131, United States
3. Photo-Electronic
Hybrids Research Center, Korea Institute of Science and Technology, Seoul 02792, Korea
4. Dipartimento
di Scienza dei Materiali, Università degli Studi di Milano-Bicocca, I-20125 Milano, Italy