International
Tables for
Crystallography
Volume B
Reciprocal space
Edited by U. Shmueli

International Tables for Crystallography (2010). Vol. B, ch. 2.5, p. 356   | 1 | 2 |

Section 2.5.4.1. Introduction

B. K. Vainshteinc and B. B. Zvyagind

2.5.4.1. Introduction

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Electron-diffraction structure analysis (EDSA) (Vainshtein, 1964[link]) based on electron diffraction (Pinsker, 1953[link]) is used for the investigation of the atomic structure of matter together with X-ray and neutron diffraction analysis. The peculiarities of EDSA, as compared with X-ray structure analysis, are defined by a strong interaction of electrons with the substance and by a short wavelength λ. According to the Schrödinger equation (see Section 5.2.2[link] ) the electrons are scattered by the electrostatic field of an object. The values of the atomic scattering amplitudes, fe, are three orders higher than those of X-rays, fx, and neutrons, fn. Therefore, a very small quantity of a substance is sufficient to obtain a diffraction pattern. EDSA is used for the investigation of very thin single-crystal films, of ~5–50 nm polycrystalline and textured films, and of deposits of finely grained materials and surface layers of bulk specimens. The structures of many ionic crystals, crystal hydrates and hydro-oxides, various inorganic, organic, semiconducting and metallo-organic compounds, of various minerals, especially layer silicates, and of biological structures have been investigated by means of EDSA; it has also been used in the study of polymers, amorphous solids and liquids.

Special areas of EDSA application are: determination of unit cells; establishing orientational and other geometrical relationships between related crystalline phases; phase analysis on the basis of [d_{hkl}] and [I_{hkl}] sets; analysis of the distribution of crystallite dimensions in a specimen and inner strains in crystallites as determined from line profiles; investigation of the surface structure of single crystals; structure analysis of crystals, including atomic position determination; precise determination of lattice potential distribution and chemical bonds between atoms; and investigation of crystals of biological origin in combination with electron microscopy (Vainshtein, 1964[link]; Pinsker, 1953[link]; Zvyagin, 1967[link]; Pinsker et al., 1981[link]; Dorset, 1976[link]; Zvyagin et al., 1979[link]).

There are different kinds of electron diffraction (ED) depending on the experimental conditions: high-energy (HEED) (above 30–200 kV), low-energy (LEED) (10–600 V), transmission (THEED) and reflection (RHEED). In electron-diffraction studies use is made of special apparatus – electron-diffraction cameras in which the lens system located between the electron source and the specimen forms the primary electron beam, and the diffracted beams reach the detector without aberration distortions. In this case, high-resolution electron diffraction (HRED) is obtained. ED patterns may also be observed in electron microscopes by a selected-area method (SAD). Other types of electron diffraction are: MBD (microbeam), HDD (high-dispersion), CBD (convergent-beam), SMBD (scanning-beam) and RMBD (rocking-beam) diffraction (see Sections 2.5.2[link] and 2.5.3[link]). The recent development of electron diffractometry, based on direct intensity registration and measurement by scanning the diffraction pattern against a fixed detector (scintillator followed by photomultiplier), presents a new improved level of EDSA which provides higher precision and reliability of structural data (Avilov et al., 1999[link]; Tsipursky & Drits, 1977[link]; Zhukhlistov et al., 1997[link], 1998[link]; Zvyagin et al., 1996[link]).

Electron-diffraction studies of the structure of molecules in vapours and gases is a large special field of research (Vilkov et al., 1978[link]). See also Stereochemical Applications of Gas-Phase Electron Diffraction (1988)[link].

References

Stereochemical Applications of Gas-Phase Electron Diffraction (1988). Part A, edited by I. Hargittai & M. Hargittai. New York: VCH.
Avilov, A. S., Kuligin, A. K., Pietsch, U., Spence, J. C. H., Tsirelson, V. G. & Zuo, J. M. (1999). Scanning system for high-energy electron diffractometry. J. Appl. Cryst. 32, 1033–1038.
Dorset, D. L. (1976). The interpretation of quasi-kinematical single-crystal electron diffraction intensity data from paraffins. Acta Cryst. A32, 207–215.
Pinsker, Z. G. (1953). Electron Diffraction. London: Butterworth.
Pinsker, Z. G., Zvyagin, B. B. & Imamov, R. M. (1981). Principal results of electron-diffraction structural investigations. Sov. Phys. Crystallogr. 26, 669–674.
Tsipursky, S. I. & Drits, V. A. (1977). Efficiency of electronometric intensity registration at electron diffraction structural studies. Izv. Akad. Nauk SSSR Ser. Fiz. 41, 2263–2271.
Vainshtein, B. K. (1964). Structure Analysis by Electron Diffraction. Oxford: Pergamon Press.
Vilkov, L. V., Mastryukov, V. S. & Sadova, N. I. (1978). Determination of Geometrical Structure of Free Molecules. Leningrad: Khimiya.
Zhukhlistov, A. P., Avilov, A. S., Ferraris, G., Zvyagin, B. B. & Plotnikov, V. P. (1997). Statistical distribution of hydrogen over three positions in the brucite Mg(OH)2 structure from electron diffractometry data. Crystallogr. Rep. 42, 774–777.
Zhukhlistov, A. P. & Zvyagin, B. B. (1998). Crystal structure of lizardite 1T from electron diffractometry data. Crystallogr. Rep. 43, 950–955.
Zvyagin, B. B. (1967). Electron-Diffraction Analysis of Clay Mineral Structures. New York: Plenum.
Zvyagin, B. B., Vrublevskaya, Z. V., Zhukhlistov, A. P., Sidorenko, S. V., Soboleva, A. F. & Fedotov, A. F. (1979). High-Voltage Electron Diffraction Investigations of Layered Minerals. Moscow: Nauka.
Zvyagin, B. B., Zhukhlistov, A. P. & Plotnikov, A. P. (1996). Development of the electron diffractometry of minerals. Structural studies of crystals. (Coll. Works 75th Anniversary Acad. B. K. Vainshtein.) Nauka-Physmathlit, pp. 225–234.








































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