1. Electrical Insulation Research Center, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269, United States
2. Department of Materials Science and Engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft, The Netherlands
3. Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269, United States
4. Institute of Physics and Astronomy, Faculty of Science, University of Potsdam, 14476 Potsdam-Golm, Germany