1. Department of Chemistry, Queen's University, Kingston, Ontario, Canada K7L 3N6; Xerox Research Center of Canada, 2660 Speakman Drive, Mississauga, Ontario, Canada L5K 2L1; Steacie Institute for Molecular Science, National Research Council, 100 Sussex Drive, Ottawa, Canada K1A 0R6; and Institute for Microstructural Science, National Research Council, Ottawa, Canada K1A 0R6