1. Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, MPA-NHMFL, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, NanoMaterials, Ltd., Weizman Science Park, Building 18, Nes Ziona 74140, Israel, and Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel