1. Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
2. California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
3. Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, United States
4. Department of Chemistry and Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47904, United States
5. Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States
6. Department of Chemistry and the International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
7. Department of Mathematics, University of California, Los Angeles, Los Angeles, California 90095, United States
8. Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
9. Department of Mathematics and Statistics, San Diego State University, San Diego, California 92182, United States