1. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180, United States
3. Center for
Nanochemistry, Beijing National Laboratory for Molecular Sciences,
Key Laboratory for the Physics and Chemistry of Nanodevices, State
Key Laboratory for Structural Chemistry of Unstable and Stable Species,
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China
4. Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States