1. California
NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
2. Department of Physics & Astronomy, University of California, Los Angeles, Los Angeles, California 90095, United States
3. Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
4. Department
of Chemistry and the International Institute for Nanotechnology, Northwestern University, Evanston, Illinois 60208, United States
5. Institute
of Inorganic Chemistry, Academy of Sciences of the Czech Republic, v.v.i., č.p. 1001, 250 68 Husinec-Řež, Czech Republic
6. Department of Materials Science & Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States