1. Department of Physics; University of California at Berkeley; Berkeley CA 94720 USA
2. Materials Science Division; Lawrence Berkeley National Laboratory (LBNL); Berkeley CA 94720 USA
3. National Center for Electron Microscopy (NCEM), Molecular Foundry; Lawrence Berkeley National Laboratory (LBNL); Berkeley CA 94720 USA
4. Kavli Energy NanoSciences Institute at the University of California; Berkeley California 94720 USA