1. Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716-2522 U. S. A. (C. D., M.L.S., M.A.H., E.J.G.); Physikalische Chemie, Universität Dortmund, 44221 Dortmund, Germany (G.N.); and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 U.S.A. (D.L.P.)