Electron microscopy, high-resolution

Flueli M, Buffat P A and Borel J P 1988 Real time observation by high resolution electron microscopy (HREM) of the coalescence of small gold particles in the electron beam Surf. Sc/. 202 343... 

There are three primary image modes that are used in conventional TEM work, bright-field microscopy, dark-field microscopy, and high-resolution electron microscopy. In practice, the three image modes differ in the way in which an objective diaphragm is used as a filter in the back focal plane. 

A special mention is in order of high-resolution electron microscopy (HREM), a variant that permits columns of atoms normal to the specimen surface to be imaged the resolution is better than an atomic diameter, but the nature of the image is not safely interpretable without the use of computer simulation of images to check whether the assumed interpretation matches what is actually seen. Solid-state chemists studying complex, non-stoichiometric oxides found this image simulation approach essential for their work. The technique has proved immensely powerful, especially with respect to the many types of defect that are found in microstructures. 

Good semi-quantitative agreements are found in diffraction patterns and proposed models obtained by molecular-dynamics[14], because the results of the ex-periments[31-34] are consistent with the atomic models proposed by us[14]. However, in the present state of high-resolution electron microscopy, taking into account, moreover, the number of sheets and the complicated geometry of the helix, it seems unlikely to directly visualize the pentagon-hexagon pairs. 

The author wishes to thank Dr. J.B. Cohen for supplying samples of Pt and Pd on alumina and silica and Drs. J. Schwank and A.K. Dayte for samples of Ru and Au on magnesia and silica. This work was supported by the US Department of Energy under Contract DMR-76ER02995 and has make use of the resources of the ASU Faoiltity for High Resolution Electron Microscopy, supported by NSF grant DMR 8306501. 

High resolution electron microscopy has recently demonstrated the capability to directly resolve the atomic structure of surfaces on small particles and thin films. In this paper we briefly review experimental observations for gold (110) and (111) surfacest and analyse how these results when combined with theoretical and experimental morphological studies, influence the interpretation of geometrical catalytic effects and the transfer of bulk surface experimental data to heterogeneous catalysts. 

All of these methods suffer from one serious shortcoming - the spatial resolution is relatively poor ( 10A) and Information about the catalytically interesting region of the particle, namely the surface structure, is then not available. One particular technique, high resolution electron microscopy, has for many years been slowly... 

In the present study, we synthesized in zeolite cavities Co-Mo binary sulfide clusters by using Co and Mo carbonyls and characterized the clusters by extended X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and high resolution electron microscopy (HREM). The mechanism of catalytic synergy generation in HDS is discussed. 

J. C. H. Spence, High-Resolution Electron Microscopy. 3rd ed., Oxford University Press, Oxford, 2003. 

High-Resolution Electron Microscopy and Electron Energy Loss Spectroscopy... 

Nobel Symposium No. 47 on "High Resolution Electron Microscopy", Chemica Scripta 1979, 14, 167. 

Improvements in the resolution and versatility of microscopic techniques have come about rapidly. TEM, STEM, and high-resolution electron microscopy have helped the catalytic chemist to analyze the effects of metal-support interactions and particle-size effects—developments that will probably lead to improvements in commercial technologies. Several novel analytical methods, arising from very clever experimentation, were discussed at the... 

Particles of face-centered cubic metals of diameter 5 nm of more have been studied extensively by high resolution electron microscopy, diffraction and other methods. It has been shown that such particles are usually multiply twinned, often conforming approximately the idealized models of decahedral and icosahedral particles consisting of clusters of five or twenty tetrahedrally... 

The original work reported in this article was supported by NSF grant DMR-7926460 and Department of Energy Contract EY-76-S-02-2995 and made use of the resources of the Facility for High Resolution Electron Microscopy within the Center for Solid State Science, ASU, supported by NSF grant CHE-7916098. 

Oleshko, V. et al., High resolution electron microscopy and electron energy-loss spectroscopy of giant palladium clusters, Z. Phys. D., 34, 283, 1995. 

Duff, D.G. et al., Structural characterization of colloidal platinum by high resolution electron microscopy and EXAFS analysis, Angew. Chem. 101, 610, 1989 Angew. Chem. Int. Ed. Engl., 28, 590,1989. 

B. High-Resolution Electron Microscopy of Molecular Crystals.77... 

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