1. Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, Nebraska 68198-6805, Ash Stevens, Inc., 5861 John C. Lodge Freeway, Detroit, Michigan 48202-3398, Department of Analytical Chemistry and Applied Spectroscopy, Laser Centre, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands, and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111