1. Department of Chemistry, Stanford University, Stanford, California 94305-5080,
United States
2. Department of Chemistry, Tufts University, Medford, Massachusetts 02155-5813,
United States
3. Institute
of Physical Chemistry, University of Göttingen, Tammannstrasse 6, 37077
Göttingen, Germany
4. Cancer Center, Tufts Medical Center, Boston, Massachusetts 02110,
United States