1. Department of Chemical Engineering, University of California, Berkeley, California 94720
2. Department of Physics, Yale University, New Haven, Connecticut 06520
3. Argonne National Laboratory, Argonne, Illinois 60439
4. Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
5. Materials Sciences Division and Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720