1. Department of Electrical Engineering, California State University, Long Beach, California 90840, United States
2. Department of Physics, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States
3. Department of Chemistry and Biochemistry, University of Minnesota, Duluth, Minnesota 55812, United States
4. Department of Chemistry, University of Waterloo, 200 University Ave., Waterloo, Ontario N2L 3G1, Canada
5. Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States