1. Department of Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269, USA
2. Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, USA
3. Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506, USA
4. Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, USA
5. Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA