1. Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ 08854, USA.
2. Department of Chemical and Biochemical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA.
3. The Institute for Advanced Materials, Devices and Nanotechnology (IAMDN), Rutgers, The State University of New Jersey, 607 Taylor Road, Piscataway, NJ 08854, USA.
4. Department of Physics, Tsinghua University, Beijing 100084, China.