1. Department
of Chemistry, University of California, Davis, California 95616, United States
2. Physical
Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
3. Department
of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
4. Advanced
Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
5. Department
of Chemistry and Biochemistry, University of California at Santa Cruz, Santa
Cruz, California 95064, United States