1. Department of Physics, University of California, Santa Barbara, California 93106; Marine Biotechnology Center and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106; Department of Chemistry, University of California, Santa Barbara, California 93106; Materials Research Laboratory, University of California, Santa Barbara, California 93106; and Department of Physics, Luleå University of Technology, S-97187 Luleå, Sweden