1. Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
2. Department of Materials Science and Engineering and Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
3. NIST Center for Neutron Research, Gaithersburg, Maryland 20899-1070, United States
4. Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, United States