30 H i g h - R e s o l u t i o n E l e c t r o n M i c r o s c o p y and
Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 29, 2016 | http://pubs.acs.org Publication Date: March 3, 1983 | doi: 10.1021/bk-1983-0211.ch030
E l e c t r o n E n e r g y L o s s Spectroscopy J. M. THOMAS University of Cambridge, Department of Physical Chemistry, Lensfield Road, Cambridge CB2 1EP England The merit of high-resolution electron microscopy (HREM) is that it can yield structural information, in real space and at the sub-nanometric level, about materials that are not amenable to structure determination be X-ray crystallographic and other conventional techniques. Specific, localised, rather than spatially averaged information is gleaned in this way, and new structural types as well as new mechanistic details are brought to light through the application of HREM to hitherto intractable systems. The first part of the article illustrates the validity of these statements by specific reference to: (i) quasi-crystalline solids (zeolites and transition metal sulphide catalysts), and (ii) oxides and silicates in which there are intergrowths at the unit cell level as in the pyroxenoids and bismuth tungstates. Some of the new structural types discovered by HREM include a spatial form of graphite intercalate, multiply-twinned zeolites, and ring-chain intergrowths amonsgt silicates and their germanate analogues. HREM is also especially useful in evaluating mechanisms of structural transfrormations and in clarifying the nature of crystalline imperfections. Electron energy loss spectroscopy (EELS) is a powerful new microanalytical technique, capable of detecting less than 10-20g of a particular element. The basic principles of this new method of chemical analysis is outlined. Extended, electron energy loss fine structure (EXELFS) and its potential as a new method of determining the structure of ordered or amorphous inorganic materials (applicable unlike EXAGS to materials consisting of all atoms, other than hydrogen, lighter than calcium) is also 0097-6156/83/0211-0445$07.75/0 © 1983 American Chemical Society Chisholm; Inorganic Chemistry: Toward the 21st Century ACS Symposium Series; American Chemical Society: Washington, DC, 1983.
Downloaded by UNIV OF CALIFORNIA SAN DIEGO on December 29, 2016 | http://pubs.acs.org Publication Date: March 3, 1983 | doi: 10.1021/bk-1983-0211.ch030
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INORGANIC CHEMISTRY: TOWARD THE 21ST CENTURY discussed and illustrated. Future prospects, of using Compton scattering and other procedures are also outlined.
As an analytical tool high resolution electron microscopy (HREM) either alone or in conjunction with closely related techniques (such as selected area electron diffraction (SAED), ultramicro X-ray-emission spectrometry (XRES), ultramicro electron-energy-loss spectroscopy (EELS) (in EELS, because resolution is appreciable (
