1 Institute of Fluorescence and Center for Fluorescence Spectroscopy, Medical Biotechnology Center, University of Maryland Biotechnology Institute, 725 West Lombard St, Baltimore, Maryland, 21210.
2 Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, 725 West Lombard St, Baltimore, Maryland, 21201.
3 Department of Chemistry, Roberts Wesleyan College, 2301 Westside Drive, Rochester, New York, 14624.