1. Department of Chemistry, Rice University; Houston, TX 77005, USA.
2. Department of Electrical and Computer Engineering, Rice University; Houston, TX 77005, USA.
3. School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
4. Syzygy Plasmonics Inc., Houston, TX 77054, USA.
5. Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544-5263; Present address: Department of Chemistry, Boston College; Chestnut Hill, MA 02467, USA.
6. Department of Materials Science and NanoEngineering, Rice University; Houston, TX 77005, USA.
7. Department of Chemical and Biomolecular Engineering, University of California, Los Angeles; Los Angeles, CA 90095-1405 and Department of Mechanical and Aerospace Engineering and the Andlinger Center for Energy and the Environment, Princeton University; Princeton, NJ 08544-5263, USA.
8. Department of Physics and Astronomy, Rice University, Houston, TX 77005, USA.