1. Polymer Science and Engineering Department, W. M. Keck Electron Microscopy Laboratory, University of Massachusetts, Amherst, Massachusetts 01003
2. Department of Chemistry, University of Athens, Panepistimiopolis Zografou 15771, Athens, Greece, and Institute of Electronic Structure and Laser, 711 10 Heraklion, Crete, Greece
3. Polymers Research Branch, U.S. Army Research Laboratory, APG, MD 211005‐5069, and Reactor Radiation Division, NIST, Gaithersburg, Maryland 20899
4. Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama 35294