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  • 1
    Electronic Resource
    Electronic Resource
    Inversion of dynamical electron scattering to obtain the crystal potential using data from two thicknesses (2001)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 473-474 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A method is given to invert the multiple scattering of electrons in a crystalline slab to obtain the projected potential. For a fixed orientation of the incident beam of electrons, scattering data are required for two thicknesses of the crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767301006353
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  • 2
    Electronic Resource
    Electronic Resource
    Three-beam and many-beam theory in electron diffraction and its use for structure-factor phase determination in non-centrosymmetric crystal structures (1989)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 45 (1989), S. 839-851 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Closed-form expressions for three-beam dynamical transmission electron diffraction are compared. These are used as a guide to determine the best experimental conditions for the determination of structure-factor phases by convergent-beam electron diffraction in the general non-systematic case. The validity domains of Kambe's [J. Phys. Soc. Jpn (1957), 12, 1-13] 'strong coupling' approximation and Bethe's [Ann. Phys. (Leipzig) (1928), 87, 55-129] second approximation are compared, and these approximations reconciled. A comparison of many-beam calculations with experimental non-systematic CBED patterns is used to determine a three-phase invariant for CdS with an accuracy of ±5° in the electron structure-factor phase. If it is assumed that two of the phases are known exactly, the error in the third (00\bar 2) X-ray structure-factor phase would be ±0.75°. The accuracy of the method for determining phases, atomic position parameters and bonding charge distributions is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876738900913X
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  • 3
    Electronic Resource
    Electronic Resource
    Approximations for dynamical calculations of microdiffraction patterns and images of defects (1978)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 34 (1978), S. 112-116 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The calculation of dynamical elastic diffuse electron scattering from a crystal containing a point defect or dislocation may require prohibitively large amounts of computing time. Two approximations are described which greatly reduce the computer time required for these calculations, and so allow the simulation of electron-microscope images of defects at atomic resolution. The diffuse scattering expected from microdiffraction experiments can also be predicted in this way.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739478000194
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  • 4
    Electronic Resource
    Electronic Resource
    The winners of the first Ewald Medals and Award (1988)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 44 (1988), S. 767-767 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876738801013X
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  • 5
    Electronic Resource
    Electronic Resource
    Two-beam features in electron diffraction patterns – application to refinement of low-order structure factors in GaAs (1988)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 44 (1988), S. 810-820 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Progress in theoretical approaches to the refinement of structure factors and structure determination by electron diffraction is briefly reviewed. A strategy based on the use of two-beam-like features in convergent-beam electron diffraction (CBED) patterns is advocated, based on an effective potential and a reduced excitation error. Model calculations suggest inversion of the Bethe potentials to be useful. New experimental measurements for CBED rocking curves in GaAs are reported and these give the refined values V(200) = 0.432 (9), V(400) = 4.53 (4) V at 90 K, including Debye-Waller factor. The results from the inverse Bethe potential method are in excellent agreement with full many-beam calculations. These experimental values are compared with the results of recent pseudopotential total-energy calculations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767388004362
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  • 6
    Electronic Resource
    Electronic Resource
    Three-dimensional strain-field information in convergent-beam electron diffraction patterns (1982)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 38 (1982), S. 55-61 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Convergent-beam electron diffraction (CBED) patterns contain diffracted beams from higher-order Laue zones (HOLZ), in addition to the more often observed diffracted beams from the zeroth-order reciprocal lattice zone (ZOLZ) that contains the origin of the reciprocal lattice. Since HOLZ diffraction vectors have non-zero components along the incident electron beam direction, they can detect components of static real-lattice displacement fields that lie along the incident electron beam direction, an event not possible for diffracted beams normal to the incident electron beam direction (i.e. ZOLZ diffracted beams). This effect is used in the present work to determine Burgers vectors of straight dislocations and loops in silicon from observations of splitting of HOLZ lines within the forward scattered beam Bragg disk, and from splitting of Kikuchi lines associated with HOLZ Bragg reflections. The method was also applied with limited success to dislocations in aluminum; here splitting was more difficult to observe because of the rather strong diffuse background in the CBED patterns. Calculations of HOLZ line splitting due to the presence of a dislocation in the irradiated crystal volume were in good qualitative agreement with the experimental observations. Effects on CBED patterns to be expected from some partial dislocations are discussed. This CBED method can be very useful for the determination of non-ZOLZ fault vector components in an atomic resolution structure-imaging microscope. These instruments usually have specimen tilt ranges limited to about 10°; thus conventional Burgers-vector analysis is not generally possible. Finally, the present CBED results show clearly that the projection approximation generally used to interpret structure fringe images is not strictly valid. the changes in fringe images or weak-beam images from HOLZ excitations remain to be evaluated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739482000102
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  • 7
    Electronic Resource
    Electronic Resource
    Pendellösung radiation and coherent Bremsstrahlung (1986)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 42 (1986), S. 577-585 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The spontaneous emission process, which is kinematically forbidden in vacuum, may occur for kilovolt electrons traversing thin crystals as a direct result of the dynamical diffraction process which Paul Ewald was amongst the first to understand. The history of this effect is briefly reviewed. New experimental results, and the relevant theoretical background, are given for the resulting monochromatic X-ray emission lines known as coherent Bremsstrahlung and channelling radiation. The fine structure of these lines in particular is discussed, and their effects on electron energy-loss spectra described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767386098719
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  • 8
    Electronic Resource
    Electronic Resource
    Large dynamic range, parallel detection system for electron diffraction and imaging (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2102-2105 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A parallel detection system for electrons in the 10–800-kV energy range is described. The design is based on a 576×382 pixel charge-coupled device array operating at liquid-nitrogen temperature. This is coupled by fiber optics to a single-crystal YAG screen, which serves as the primary detection element. The performance of the system for quantitative electron diffraction and imaging studies is described. The system will record a maximum count of 16 000 per pixel with low noise at a frame rate of 2.5 frames per second.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1140039
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  • 9
    Electronic Resource
    Electronic Resource
    Direct observation of d -orbital holes and Cu–Cu bonding in Cu 2 O (1999)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 401 (1999), S. 49-52 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A striking feature of metal oxide chemistry is the unusual electronic and chemical behaviour of Cu(I) and Ag(I): a case in point is that detailed understanding of Cu–O bonding is essential to the theory of high-temperature copper oxide superconductors. Both cations are ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/43403
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  • 10
    Electronic Resource
    Electronic Resource
    Brightness measurements of nanometer-sized field-emission-electron sources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7041-7045 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The brightness of nanometer-sized field-emission-electron sources have been measured experimentally. Ultrasharp tungsten (111) single-crystal tips were fabricated in situ using Ne sputtering and field evaporation, and monitored using field ion microscopy. The average brightness of single-atom-terminated nanotips was found to be 3.3×108 A cm−2 sr−1 at 470 V, or 7.7×1010 A cm−2 sr−1 when extrapolated to 100 kV. These results show an improvement of about two orders of magnitude in source brightness over existing cold field-emission-electron sources, and produce a beam with greater particle flux per unit energy than those obtainable using current synchrotron/wiggler/undulator devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352371
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