1. Department of PhysicsBryn Mawr College Bryn Mawr, Pennsylvania USA
2. Nanoscale Characterization Facility Singh Center for NanotechnologyUniversity of Pennsylvania Philadelphia, Pennsylvania USA
3. Laboratory for Research on the Structure of MatterUniversity of Pennsylvania Philadelphia, Pennsylvania USA
4. Department of Chemistry and BiochemistryUniversity of California San Diego La Jolla, California USA
5. Department of Materials Science and Engineering School of Engineering and Applied ScienceUniversity of Pennsylvania Philadelphia, Pennsylvania USA