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  • 1
    Electronic Resource
    Electronic Resource
    HREM imaging of small Pt clusters dispersed in Y-zeolites (1990)
    Springer
    Catalysis letters 5 (1990), S. 1-11 
    Details
    ISSN: 1572-879X
    Keywords: HREM ; small Pt clusters ; zeolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High resolution electron microscopy (HREM) has been used to study dispersed Pt clusters in NaY- and USY-zeolites. All the samples contained 0.8% Pt and were reduced at temperatures of 300 ° C, 500 ° C and 650 ° C. The size of the Pt clusters ranged from a few å up to ∼ 30 å. When the incident electron beam was sufficiently strong, it caused some of the extremely small metal clusters to sinter. This was usually accompanied by zeolite damage. This in-situ sintering must be taken into consideration when interpreting the particle size distribution results obtained solely by TEM, especially for particles that are smaller than 10 å. The minimum phase contrast imaging condition is demonstrated to be more appropriate than optimum defocus for detecting the extremely small Pt clusters inside the zeolite structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00772087
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation and characterization of MgO surfaces by reflection electron microscopy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 20 (1992), S. 426-438 
    Details
    ISSN: 1059-910X
    Keywords: Reflection high energy electron diffraction ; Surface topography ; Chemical polishing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have employed several different methods to prepare (100) and (111) surfaces of MgO crystals. (100) surfaces prepared by simple cleaving give good reflection high energy electron diffraction (RHEED) patterns and surfaces with a high density of coarse steps. Chemical polishing of this surface results in a roughening of the topography whilst annealing in oxygen considerably smoothens the surfaces although they appear to be contaminated. Under certain conditions we find that the MgO crystals will cleave along the (111) plane. Both cleaved and mechanically polished (111) surfaces are atomically flat and reconstructed after oxygen annealing.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070200412
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of the coherence of illumination on electron microdiffraction pattern intensities (1987)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 177-183 
    Details
    ISSN: 0741-0581
    Keywords: Coherence width ; Field emission guns ; Out-of-phase domain boundaries ; Spot splitting microdiffraction ; Electrical instabilities ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Microdiffraction is capable of revealing the local structure within an area of the specimen consisting of only a few, or a few tens of, unit cells. However, the extent to which the diffraction pattern intensities can show the local structure depends strongly on the coherence of the illumination. If the coherence width of the illumination is smaller than the diameter of the electron probe at the specimen level, the details within the diffraction spots, which indicate deviations of the local structure from the periodicity of the crystal, will be lost. The differences in the amount of spot splitting observed in microdiffraction patterns from out-of-phase domain boundaries, observed with two instruments, are attributed to differences in the effective source sizes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060070305
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    Paper (German National Licenses)
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