1. Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
2. Institute of Experimental Physics, Graz University of Technology, 8010 Graz, Austria
3. Department of Chemistry, University of California, Berkeley, California 94720, USA
4. Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Stanford, California 94025, USA
5. Department of Physics, University of California, Berkeley, California 94720, USA
6. Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA