1. Department of Chemical Engineering and SUNCAT Center for Interface Science and Catalysis, Stanford University, Stanford, California 94305, United States
2. Department of Physics, AlbaNova University Center, Stockholm University, Stockholm SE-106 91, Sweden
3. Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Lemont, Illinois 60439, United States
4. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
5. Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States