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  • 1
    Online-Ressource
    Online-Ressource
    Oxford :Oxford University Press, Incorporated,
    Schlagwort(e): X-ray crystallography. ; Crystals -- Structure. ; Electronic books.
    Beschreibung / Inhaltsverzeichnis: This text focuses on the practical aspects of crystal structure analysis and provides the necessary conceptual framework for understanding and applying the technique. Many worked examples, problems with answers, and illustrations are included throughout to reinforce the material presented. Significantly updated from the first edition.
    Materialart: Online-Ressource
    Seiten: 1 online resource (406 pages)
    Ausgabe: 2nd ed.
    ISBN: 9780191569944
    Serie: International Union of Crystallography Texts on Crystallography Series ; v.13
    DDC: 548/.81
    Sprache: Englisch
    Anmerkung: Intro -- Contents -- 1 Introduction to diffraction -- 1.1 Introduction -- 1.2 X-ray scattering from electrons -- 1.3 X-ray scattering from atoms -- 1.4 X-ray scattering from a unit cell -- 1.5 The effects of the crystal lattice -- 1.6 X-ray scattering from the crystal -- 1.7 The structure-factor equation -- 1.8 The electron-density equation -- 1.9 A mathematical relationship -- 1.10 Bragg's law -- 1.11 Resolution -- 1.12 The phase problem -- 2 Introduction to symmetry and diffraction -- 2.1 The relationship between a crystal structure and its diffraction pattern -- 2.2 Translation symmetry in crystalline solids -- 2.3 Symmetry of individual molecules, with relevance to crystalline solids -- 2.4 Symmetry in the solid state -- 2.5 Diffraction and symmetry -- 2.6 Further points -- Exercises -- 3 Crystal growth and evaluation -- 3.1 Introduction -- 3.2 Protect your crystals -- 3.3 Crystal growth -- 3.4 Survey of methods -- 3.4.1 Solution methods -- 3.4.2 Sublimation -- 3.4.3 Fluid-phase growth -- 3.4.4 Solid-state synthesis -- 3.4.5 General comments -- 3.5 Evaluation -- 3.5.1 Microscopy -- 3.5.2 X-ray photography -- 3.5.3 Diffractometry -- 3.6 Crystal mounting -- 3.6.1 Standard procedures -- 3.6.2 Air-sensitive crystals -- 3.6.3 Crystal alignment -- 4 Space-group determination -- 4.1 Introduction -- 4.2 Prior knowledge and information other than from diffraction -- 4.3 Metric symmetry and Laue symmetry -- 4.4 Unit cell contents -- 4.5 Systematic absences -- 4.6 The statistical distribution of intensities -- 4.7 Other points -- 4.8 A brief conducted tour of some entries in International Tables for Crystallography, Volume A -- Exercises -- 5 Background theory for data collection -- 5.1 Introduction -- 5.2 A step-wise theoretical journey through an experiment -- 5.3 The geometry of X-ray diffraction -- 5.3.1 Real-space considerations: Bragg's law. , 5.3.2 Reciprocal-space considerations: the Ewald sphere -- 5.4 Determining the unit cell: the indexing process -- 5.4.1 Indexing: a conceptual view -- 5.4.2 Indexing procedure -- 5.5 Relating diffractometer angles to unit cell parameters: determination of the orientation matrix -- 5.6 Data-collection procedures and strategies -- 5.6.1 Criteria for selecting which data to collect -- 5.6.2 How best to measure data: the need for reflection scans -- 5.7 Extracting data intensities: data integration and reduction -- 5.7.1 Background subtraction -- 5.7.2 Data integration -- 5.7.3 Crystal and geometric corrections to data -- Exercises -- 6 Practical aspects of data collection -- 6.1 Introduction -- 6.2 Collecting data with area-detector diffractometers -- 6.3 Experimental conditions -- 6.3.1 Radiation -- 6.3.2 Temperature -- 6.3.3 Pressure -- 6.3.4 Other conditions -- 6.4 Types of area detector -- 6.4.1 Multiwire proportional chamber (MWPC) -- 6.4.2 Phosphor coupled to a TV camera -- 6.4.3 Image plate (IP) -- 6.4.4 Charge-coupled device (CCD) -- 6.5 Some characteristics of CCD area-detector systems -- 6.5.1 Spatial distortion -- 6.5.2 Non-uniform intensity response -- 6.5.3 Bad pixels -- 6.5.4 Dark current -- 6.6 Crystal screening -- 6.6.1 Unit cell and orientation matrix determination -- 6.6.2 If indexing fails -- 6.6.3 Re-harvest the reflections -- 6.6.4 Still having problems? -- 6.6.5 After indexing -- 6.6.6 Check for known cells -- 6.6.7 Unit cell volume -- 6.7 Data collection -- 6.7.1 Intensity level -- 6.7.2 Mosaic spread -- 6.7.3 Crystal symmetry -- 6.7.4 Other considerations -- Exercises -- 7 Practical aspects of data processing -- 7.1 Data reduction and correction -- 7.2 Integration input and output -- 7.3 Corrections -- 7.4 Output -- 7.5 A typical experiment? -- 7.6 Examples of more problematic cases -- 7.7 Twinning and area-detector data. , 7.8 Some other special cases (in brief) -- Exercises -- 8 Fourier syntheses -- 8.1 Introduction -- 8.2 Forward and reverse Fourier transforms -- 8.3 Some mathematical and computing considerations -- 8.4 Uses of different kinds of Fourier syntheses -- 8.4.1 Patterson syntheses -- 8.4.2 E-maps -- 8.4.3 Full electron-density maps, using (8.2) or (8.3) as they stand -- 8.4.4 Difference syntheses -- 8.4.5 2F[sub(o)] - F[sub(c)] syntheses -- 8.4.6 Other uses of difference syntheses -- 8.5 Weights in Fourier syntheses -- 8.6 Illustration in one dimension -- 8.6.1 F[sub(c)] synthesis -- 8.6.2 F[sub(o)] synthesis, as used in developing a partial structure solution -- 8.6.3 F[sub(o)] - F[sub(c)] synthesis -- 8.6.4 Full F[sub(o)] synthesis -- Exercises -- 9 Patterson syntheses for structure determination -- 9.1 Introduction -- 9.2 What the Patterson synthesis means -- 9.3 Finding heavy atoms from a Patterson map -- 9.3.1 One heavy atom in the asymmetric unit of P1 -- 9.3.2 One heavy atom in the asymmetric unit of P2[sub(1)]/c -- 9.3.3 One heavy atom in the asymmetric unit of P2[sub(1)]2[sub(1)]2[sub(1)] -- 9.3.4 One heavy atom in the asymmetric unit of Pbca -- 9.3.5 One heavy atom in the asymmetric unit of P2[sub(1)] -- 9.3.6 Two heavy atoms in the asymmetric unit of P1 and other space groups -- 9.4 Patterson syntheses giving more than one possible solution, and other problems -- 9.5 Patterson search methods -- 9.5.1 Rotation search -- 9.5.2 Translation search -- Exercises -- 10 Direct methods of crystal-structure determination -- 10.1 Amplitudes and phases -- 10.2 The physical basis of direct methods -- 10.3 Constraints on the electron density -- 10.3.1 Discrete atoms -- 10.3.2 Non-negative electron density -- 10.3.3 Random atomic distribution -- 10.3.4 Maximum value of & -- #961 -- [sup(3)](x)dV -- 10.3.5 Equal atoms -- 10.3.6 Maximum entropy. , 10.3.7 Equal molecules and & -- #961 -- (x) = const. -- 10.3.8 Structure invariants -- 10.3.9 Structure determination -- 10.3.10 Calculation of E values -- 10.3.11 Setting up phase relationships -- 10.3.12 Finding reflections for phase determination -- 10.3.13 Assignment of starting phases -- 10.3.14 Phase determination and refinement -- 10.3.15 Figures of merit -- 10.3.16 Interpretation of maps -- 10.3.17 Completion of the structure -- Exercises -- 11 An introduction to maximum entropy -- 11.1 Entropy -- 11.2 Maximum entropy -- 11.2.1 Calculations with incomplete data -- 11.2.2 Forming images -- 11.2.3 Entropy and probability -- 11.3 Electron-density maps -- 12 Least-squares fitting of parameters -- 12.1 Weighted mean -- 12.2 Linear regression -- 12.2.1 Variances and covariances -- 12.2.2 Restraints -- 12.2.3 Constraints -- 12.3 Non-linear least squares -- 12.4 Ill-conditioning -- 12.5 Computing time -- Exercises -- 13 Refinement of crystal structures -- 13.1 Equations -- 13.1.1 Bragg's law -- 13.1.2 Structure factors from the continuous electron density -- 13.1.3 Electron density from the structure amplitude and phase -- 13.1.4 Structure factor from a parameterized model -- 13.2 Reasons for performing refinement -- 13.2.1 To improve phasing so that computed electron density maps more closely represent the actual electron density -- 13.2.2 To try to verify that the structure is 'correct' -- 13.2.3 To obtain the 'best' values for the parameters in the model -- 13.3 Data quality and limitations -- 13.3.1 Resolution -- 13.3.2 Completeness -- 13.3.3 Leverage -- 13.3.4 Weak reflections and systematic absences -- 13.3.5 Standard uncertainties -- 13.3.6 Systematic trends -- 13.4 Refinement fundamentals -- 13.4.1 & -- #969 -- , the weight -- 13.4.2 & -- #947 -- [sub(1)], the observations -- 13.4.3 & -- #947 -- [sub(2)], the calculations. , 13.4.4 Issues -- 13.5 Refinement strategies -- 13.6 Under- and over-parameterization -- 13.6.1 Under-parameterization -- 13.6.2 Over-parameterization -- 13.7 Pseudo-symmetry, wrong space groups and Z' > -- 1 structures -- 13.8 Conclusion -- Exercises -- 14 Analysis of extended inorganic structures -- 14.1 Introduction -- 14.2 Disorder -- 14.2.1 Site-occupancy disorder -- 14.2.2 Positional disorder -- 14.2.3 Limits of Bragg diffraction -- 14.3 Phase transitions -- 14.4 Structure validation -- 14.5 Case history 1 - BiMg[sub(2)]VO[sub(6)] -- 14.6 Case history 2 - Mo[sub(2)]P[sub(4)]O[sub(15)] -- Exercises -- 15 The derivation of results -- 15.1 Introduction -- 15.2 Geometry calculations -- 15.2.1 Fractional and Cartesian co-ordinates -- 15.2.2 Bond distance and angle calculations -- 15.2.3 Dot products -- 15.2.4 Transforming co-ordinates -- 15.2.5 Standard uncertainties -- 15.2.6 Assessing significant differences -- 15.3 Least-squares planes and dihedral angles -- 15.3.1 Conformation of rings and other molecular features -- 15.4 Hydrogen atoms and hydrogen bonding -- 15.5 Displacement parameters -- 15.5.1 & -- #946 -- s, Bs and Us -- 15.5.2 'The equivalent isotropic displacement parameter' -- 15.5.3 Symmetry and anisotropic displacement parameters -- 15.5.4 Models of thermal motion and geometrical corrections: rigid-body motion -- 15.5.5 Atomic displacement parameters and temperature -- Exercises -- 16 Random and systematic errors -- 16.1 Random and systematic errors -- 16.2 Random errors and distributions -- 16.2.1 Measurement errors -- 16.2.2 Describing data -- 16.2.3 Theoretical distributions -- 16.2.4 Expectation values -- 16.2.5 The standard error on the mean -- 16.3 Taking averages -- 16.3.1 Testing for normality using a histogram -- 16.3.2 The & -- #967 -- [sup(2)] test for normality -- 16.3.3 Averaging data when & -- #967. , [sup(2)sub(red)]»1.
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  • 2
    Online-Ressource
    Online-Ressource
    Les Ulis :EDP Sciences,
    Schlagwort(e): X-rays--Diffraction. ; Electronic books.
    Beschreibung / Inhaltsverzeichnis: No detailed description available for "La cristallographie aux rayons X".
    Materialart: Online-Ressource
    Seiten: 1 online resource (135 pages)
    Ausgabe: 1st ed.
    ISBN: 9782759822263
    Serie: Enseignement SUP-Chimie Series
    Sprache: Französisch
    Anmerkung: Couverture -- Avant-propos -- Sommaire -- 1. Aspects fondamentaux de cristallographie aux rayons X -- 1.1. Introduction -- 1.2. Comparaison de la cristallographie avec les autres techniques de détermination structurale -- 1.3. L'analogie de l'œil et du microscope -- 1.4. Principes fondamentaux de l'état cristallin -- 1.5. Diffraction des rayons X par les molécules et par les cristaux -- 1.6. Géométrie et symétrie de la diffraction des rayons X -- 1.7. Les intensités des rayons diffractés -- 1.8. Les sources de rayons X -- 1.9. Résumé -- 1.10. Exercices -- 2. La cristallographie aux rayons X en pratique -- 2.1. Introduction -- 2.2. La préparation et la sélection des échantillons -- 2.3. Mesure des figures de diffraction -- 2.4. Obtenir la géométrie et la symétrie de la maille -- 2.5. La mesure des intensités -- 2.6. Réduction de données -- 2.7. Résolution de structure -- 2.8. Compléter la structure basique -- 2.9. Affiner la structure -- 2.10. Désordre, macle et la détermination de la « structure absolue » -- 2.11. Présenter et interpréter les résultats -- 2.12. Archiver et présenter les structures cristallines -- 2.13. Résumé -- 2.14. Exercices -- 3. Études de cas de cristallographie aux rayons X -- 3.1. Introduction -- 3.2. Étude de cas 1 : un complexe de thiolate de mercure -- 3.3. Étude de cas 2 : un complexe chiral de rhodium solvaté -- 3.4. Étude de cas 3 : des microcristaux d'un composé organique chiral -- 3.5. Étude de cas 4 : chaîne de coordination de métal -- 3.6. Étude de cas 5 : un palladium en complexe avec une phosphine volumineuse pour des études de catalyse -- 3.7. Résumé -- 3.8. Exercices -- 4. Sujets associés -- 4.1. Introduction -- 4.2. Diffraction de neutrons par un cristal unique -- 4.3. Diffraction par des échantillons en poudre -- 4.4. Cristallographie des macromolécules biologiques. , 4.5. Prédiction de structure cristalline -- 4.6. Résumé -- 4.7. Exercices -- Glossaire -- Bibliographie -- Index.
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  • 3
    Publikationsdatum: 2014-02-28
    Beschreibung: Journal of the American Chemical Society DOI: 10.1021/ja412964r
    Print ISSN: 0002-7863
    Digitale ISSN: 1520-5126
    Thema: Chemie und Pharmazie
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  • 4
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 5
    ISSN: 1520-6041
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 6
    ISSN: 1520-6041
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 64 (1942), S. 1294-1296 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Inorganic chemistry 20 (1981), S. 1562-1566 
    ISSN: 1520-510X
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Inorganic chemistry 21 (1982), S. 1897-1901 
    ISSN: 1520-510X
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Inorganic chemistry 27 (1988), S. 2653-2660 
    ISSN: 1520-510X
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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