1. Applied Science and Technology Graduate Group, University of California, Berkeley, California 94720
2. Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720
3. Department of Physics, University of Wisconsin—Madison, Madison, Wisconsin 53706
4. The Molecular Foundry, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720
5. Department of Chemistry, University of California, Berkeley, California 94720
6. Department of Materials Sciences and Engineering, University of California, Berkeley, California 94720