22,970 research outputs found

    Structure determination of PF3 adsorption on Cu(100) using X-ray standing waves

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    The local structure of the Cu(100)c(4x2)-PF3 adsorption phase has been investigated through the use of normal-incidence X-ray standing waves (NIXSW), monitored by P 1s and F 1s photoemission, together with P K-edge near-edge X-ray absorption fine structure (NEXAFS). NEXAFS shows the molecule to be oriented with its C3v symmetry axis essentially perpendicular to the surface, while the P NIXSW data show the molecule to be adsorbed in atop sites 2.37±0.04 Å above the surface, this distance corresponding to the Cu-P nearest-neighbour distance in the absence of any surface relaxation. F NIXSW indicates a surprisingly small height difference of the P and F atoms above the surface 0.44±0.06 Å, compared with the value expected for an undistorted gas-phase geometry of 0.77 Å, implying significant increases in the F-P-F bond angles. In addition, however, the F NIXSW data indicate that the molecules have a well-defined azimuthal orientation with a molecular mirror plane aligned in a substrate mirror plane, and with a small (5-10°) tilt of the molecule in this plane such that the two symmetrically-equivalent F atoms in each molecule are tilted down towards the surface

    Should surface science exploit more quantitative experiments?

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    In recent years two particular methods, scanning probe microscopy and theoretical total energy calculations (based, particularly, on density functional theory), have led to major advances in our understanding of surface science. However, performed to the exclusion of more ‘traditional’ experimental methods that provide quantitative information on the composition, vibrational properties, adsorption and desorption energies, and on the electronic and geometrical structure, the interpretation of the results can be unnecessarily speculative. Combined with these methods, on the other hand, they give considerable added power to the long-learnt lesson of the need to use a range of complementary techniques to unravel the complexities of surface phenomena

    A new species of the beetle genus Brachypsectra from the Dominican Republic : with fossil connections (Coleoptera: Brachypsectridae)

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    With the description of Brachypsectra uiuafosile n. sp., from the Cabo Rojo desert area of Hispaniola, the beetle family Brachypsectridae now contains 4 described species. The family was originally known from the Dominican Republic by Miocene amber fossils oflarvae. Genitalia are illustrated for the first time for the family. Relationships of the family within the Elateroidea are briefly discussed

    The Asian mango flower beetle, Protaetia fusca (Herbst), and Euphoria sepulcralis (Fabricius) in Florida and the West Indies (Coleoptera: Scarabaeidae: Cetoniinae)

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    The mango flower beetle, Protaetia fusca (Herbst), an Asiatic pest of several commercial crops, was first found in Florida in 1985. All subsequent Florida specimens are recorded here, as well as the first documented records from the Bahamas and Barbados. Illustrations are provided and comparisons are made to the similar native Euphoria sepulcralis (Fabricius), which is also recorded for the first time from the Bahamas. Extensive host records and a bibliography (especially tracking P. fusca spread in Hawaii) are included

    Obituary: Jacob Brodzinsky (January 17,1918 - February 25, 2003)

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    Earlier this year, at the age of 85, Major Jacob Brodzinsky passed away at his home in Santo Domingo. It is with great sadness that I write this obituary, because Jake was a great personal friend and professional colleague for over 30 years. He leaves a wife, Marianela (Mañeña) Lopez-Penha, whom he married on April 26,1964, and two lovely daughters, Sibylla and Raquel

    Legal and Investment Standards of Trustees

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    The genus Cotinis Burmeister in the eastern United States,with description of a new species from the Florida Keys, including a checklist of the genus (Coleoptera: Scarabaeidae: Cetoniinae)

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    In the eastern United States, the genus Cotinis Burmeister previously contained only C. nitida (L.), the common economic pest known as the "Green June Beetle". A new species from the Florida Keys, Cotinis aliena, is here described and illustrated. A checklist is provided for the genus, which includes 27 valid New World species, and 44 synonyms
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