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  • X-ray diffractionMarsextraterrestrial mineralogyCuriosity rover  (1)
  • enrichment ratioHirshfeld surface analysiscrystal packingfingerprint plots  (1)
  • International Union of Crystallography (IUCr)  (2)
  • EMBO Press
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2010-2014  (2)
  • 2005-2009
Collection
Keywords
Publisher
  • International Union of Crystallography (IUCr)  (2)
  • EMBO Press
  • Essen : Verl. Glückauf
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
Years
  • 2010-2014  (2)
  • 2005-2009
Year
  • 1
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    The enrichment ratio of atomic contacts in crystals, an indicator derived from the Hirshfeld surface analysis (2014)
    International Union of Crystallography (IUCr)
    In: IUCrJ
    Details
    Publication Date: 2014-04-08
    Description: The partitioning of space with Hirshfeld surfaces enables the analysis of fingerprint molecular interactions in crystalline environments. This study uses the decomposition of the crystal contact surface between pairs of interacting chemical species to derive an enrichment ratio. This quantity enables the analysis of the propensity of chemical species to form intermolecular interactions with themselves and other species. The enrichment ratio is obtained by comparing the actual contacts in the crystal with those computed as if all types of contacts had the same probability to form. The enrichments and contact tendencies were analyzed in several families of compounds, based on chemical composition and aromatic character. As expected, the polar contacts of the type H...N, H...O and H...S, which are generally hydrogen bonds, show enrichment values larger than unity. O...O and N...N contacts are impoverished while H...H interactions display enrichment ratios which are generally close to unity or slightly lower. In aromatic compounds, C...C contacts can display large enrichment ratios due to extensive π...π stacking in the crystal packings of heterocyclic compounds. C...C contacts are, however, less enriched in pure (C,H) hydrocarbons as π...π stacking is not so favourable from the electrostatic point of view compared with heterocycles. C...H contacts are favoured in (C,H) aromatics, but these interactions occur less in compounds containing O, N or S as some H atoms are then involved in hydrogen bonds. The study also highlights the fact that hydrogen is a prefered interaction partner for fluorine.
    Keywords: enrichment ratioHirshfeld surface analysiscrystal packingfingerprint plots
    Electronic ISSN: 2052-2525
    Topics: Geosciences , Physics
    Published by International Union of Crystallography (IUCr)
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  • 2
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    The first X-ray diffraction measurements on Mars (2014)
    International Union of Crystallography (IUCr)
    In: IUCrJ
    Details
    Publication Date: 2014-11-12
    Description: The Mars Science Laboratory landed in Gale crater on Mars in August 2012, and the Curiosity rover then began field studies on its drive toward Mount Sharp, a central peak made of ancient sediments. CheMin is one of ten instruments on or inside the rover, all designed to provide detailed information on the rocks, soils and atmosphere in this region. CheMin is a miniaturized X-ray diffraction/X-ray fluorescence (XRD/XRF) instrument that uses transmission geometry with an energy-discriminating CCD detector. CheMin uses onboard standards for XRD and XRF calibration, and beryl:quartz mixtures constitute the primary XRD standards. Four samples have been analysed by CheMin, namely a soil sample, two samples drilled from mudstones and a sample drilled from a sandstone. Rietveld and full-pattern analysis of the XRD data reveal a complex mineralogy, with contributions from parent igneous rocks, amorphous components and several minerals relating to aqueous alteration. In particular, the mudstone samples all contain one or more phyllosilicates consistent with alteration in liquid water. In addition to quantitative mineralogy, Rietveld refinements also provide unit-cell parameters for the major phases, which can be used to infer the chemical compositions of individual minerals and, by difference, the composition of the amorphous component.
    Keywords: X-ray diffractionMarsextraterrestrial mineralogyCuriosity rover
    Electronic ISSN: 2052-2525
    Topics: Geosciences , Physics
    Published by International Union of Crystallography (IUCr)
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