1. Department of Polymer Engineering, The University of Akron, Akron, Ohio 44325, United States
2. Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973, United States
3. Department of Chemistry, University of Arkansas at Little Rock, Little Rock, Arkansas 72204, United States
4. IBM Research Division, Almaden Research Center, San Jose, California 95120-6099, United States