1. Department of Polymer Science University of Akron Akron OH 44325 USA
2. Department of Chemistry Tsinghua University Beijing 100084 P. R. China
3. X-Ray Science Division Advanced Photon Source Argonne National Laboratory Argonne IL 60439 USA
4. Department of Chemistry and Biochemistry Northern Illinois University DeKalb IL 60115 USA
5. Material Science Division Argonne National Laboratory Argonne IL 60439 USA
6. Department of Chemistry University of Akron Akron OH 44325 USA