1. Department
of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
2. Diamond Nanotechnologies
Inc., Boston, Massachusetts 02134, United States
3. Stanford
Synchrotron Radiation Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
4. Center
for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States