1. Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive, College Park, Maryland 20742, United States
2. Fakultat für Physik, Center for NanoScience and Munich Quantum Center, Ludwig-Maximilians-Universitat München, Geschwister-Scholl-Platz 1, D-80539 München, Germany
3. Center for Integrated Nanotechnologies, Materials Physics and Applications Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
4. Joint Quantum Institute, National Institute of Standards and Technology, Gaithersburg, Maryland 20902, United States
5. Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, United States