1. Departments of Chemistry and Chemical & Environmental Engineering, University of California, Riverside, California 92521-0403, Department of Chemistry, Advanced Carbon Materials Center, University of Kentucky, Lexington, Kentucky 40506-0055, Bell Laboratories, Lucent Technologies, Murray Hill, New Jersey 07974, Department of Materials Chemistry, P.O. Box 124, Lund University, 221 00 Lund, Sweden, and Solid State Chemistry Laboratory, Materials Science Center, University of Groningen, The Netherlands