1. Department of Chemistry, Stanford University, Stanford, California 94305, United States
2. Department of Applied Physics, Stanford University, Stanford, California 94305, United States
3. Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, California 94720, United States
4. Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States