Browsing by Author "Dittrich, B"

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    On the temperature dependence of H-Uiso in the riding hydrogen model
    (Acta Crystallographica, 2014-07) Lübben, J; Volkmann, C; Grabowsky, S; Edwards, AJ; Morgenroth, W; Fabbiani, FPA; Sheldrick, GM; Dittrich, B
    The temperature dependence of H-Uiso in N-acetyl-L-4-hydroxyproline monohydrate is investigated. Imposing a constant temperature-independent multiplier of 1.2 or 1.5 for the riding hydrogen model is found to be inaccurate, and severely underestimates H-Uiso below 100 K. Neutron diffraction data at temperatures of 9, 150, 200 and 250 K provide benchmark results for this study. X-ray diffraction data to high resolution, collected at temperatures of 9, 30, 50, 75, 100, 150, 200 and 250 K (synchrotron and home source), reproduce neutron results only when evaluated by aspherical-atom refinement models, since these take into account bonding and lone-pair electron density; both invariom and Hirshfeld-atom refinement models enable a more precise determination of the magnitude of H-atom displacements than independent-atom model refinements. Experimental efforts are complemented by computing displacement parameters following the TLS+ONIOM approach. A satisfactory agreement between all approaches is found. © International Union of Crystallography
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    Plasmonic twinned silver nanoparticles with molecular precision
    (Springer Nature, 2016-09-09) Yang, HY; Wang, Y; Chen, X; Zhao, XJ; Gu, L; Huang, HQ; Yan, JZ; Xu, CO; Li, G; Wu, JC; Edwards, AJ; Dittrich, B; Tang, ZC; Wang, DD; Lehtovaara, L; Häkkinen, H; Zheng, NF
    Determining the structures of nanoparticles at atomic resolution is vital to understand their structure–property correlations. Large metal nanoparticles with core diameter beyond 2 nm have, to date, eluded characterization by single-crystal X-ray analysis. Here we report the chemical syntheses and structures of two giant thiolated Ag nanoparticles containing 136 and 374 Ag atoms (that is, up to 3 nm core diameter). As the largest thiolated metal nanoparticles crystallographically determined so far, these Ag nanoparticles enter the truly metallic regime with the emergence of surface plasmon resonance. As miniatures of fivefold twinned nanostructures, these structures demonstrate a subtle distortion within fivefold twinned nanostructures of face-centred cubic metals. The Ag nanoparticles reported in this work serve as excellent models to understand the detailed structure distortion within twinned metal nanostructures and also how silver nanoparticles can span from the molecular to the metallic regime. © The Author(s) 2016, Creative Commons Attribution 4.0 International License.