1. Department of Chemistry and Biochemistry and the California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
2. WPI Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0040, Japan
3. Applied Research Institute and Computational Science and Engineering, College of Engineering, University of Illinois at Urbana−Champaign, Champaign, Illinois 61820, United States