1. Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, USA.
2. Department of Physics and Electrical Engineering, Columbia University, 3000 Broadway, New York, NY 10027, USA.
3. Department of Applied Physics and Applied Mathematics, Columbia University, 3000 Broadway, New York, NY 10027, USA.
4. Department of Mechanical Engineering, Columbia University, 3000 Broadway, New York, NY 10027, USA.
5. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973, USA.