1. Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
2. School of Materials Science and Engineering, Southeast University, Nanjing 211189, P.R. China
3. Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
4. National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States