1. Department of Chemistry, University of California, Berkeley, California 94720-1460, Institute for Lasers, Photonics and Biophotonics and Department of Chemistry, State University of New York, Buffalo, New York 14260-3000, and Polymer Branch, Air Force Research Laboratory/MLBP, 2941 P Street, Suite 136, Area B, Building 654, Wright-Patterson AFB, Ohio 45433-7750