1. Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
2. Department of Physics, Nanoscience Center, University of Jyväskylä, Fl-40014 Jyväskylä, Finland
3. Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
4. Department of Chemistry, Nanoscience Center, University of Jyväskylä, Fl-40014 Jyväskylä, Finland