1. Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
2. Department
of Physics and Astronomy, Department of Electrical and Computer Engineering,
Laboratory for Nanophotonics, Rice University, Houston, Texas 77005, United States
3. School
of Public Health, Nantong University, Nantong, Jiangsu 226019, China
4. USC Nanocenter, University of South Carolina, Columbia, South Carolina 29208, United States