1. Department of Chemistry, Stanford University, Stanford, California94305, United States
2. Department of Chemistry, Stony Brook University, Stony Brook, New York11794, United States
3. Department of Physics, University of Oxford, OxfordOX1 3PU, United Kingdom
4. Department of Chemistry, University of California, Berkeley, California94720, United States
5. STROBE, National Science Foundation Science and Technology Center, University of California Berkeley, Berkeley, California94720, United States
6. Department of Physics, University of California Berkeley, Berkeley, California94720, United States
7. Materials Science Division and Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California94720, United States
8. Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California94720, United States
9. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California94025, United States