1. Department
of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
2. School
of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States
3. FEI Corporation, 5350
NE Dawson Creek Drive, Hillsboro, Oregon 97124, United States
4. National
Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
5. Graphenea
S.A., 76 Tolosa Hiribidea, Donostia-San
Sebastian, E-20018, Spain