1. Department of Materials Science and Engineering, State University of New York at Stony Brook, Stony Brook, New York 11794-2275; ExxonMobil Research and Engineering Company, Annandale, New Jersey 08801; ExxonMobil Chemical Company, Polymer Science and Butyl Technology Divisions, Baytown, Texas 77520; Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899; Department of Physics, North Carolina State University, Raleigh, North Carolina 27695; and Brookhaven...