1. Interdisciplinary Nanotoxicity Center, Department of Chemistry, Physics and Atmospheric Sciences, Jackson State University, Jackson, Mississippi 39217, United States
2. Department of Chemistry and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
3. Department of Chemistry and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
4. Department of Chemistry and Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States