1. Department of Chemistry, Stanford University, Stanford, California 94305, United States
2. Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
3. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
4. Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
5. University of Rhode Island, Kingston, Rhode Island 02881, United States