Electron diffraction, application

Haigittai M, Haigittai M (2010) Electron diffraction applications. In John L, George T, David K (eds) Encyclopedia of spectroscopy and spectrometry, vol 1, 2nd edn. Elsevier, Oxford, PP 456-460... 

Transmission electron microscopy (TEM) can resolve features down to about 1 nm and allows the use of electron diffraction to characterize the structure. Since electrons must pass through the sample however, the technique is limited to thin films. One cryoelectron microscopic study of fatty-acid Langmuir films on vitrified water [13] showed faceted crystals. The application of TEM to Langmuir-Blodgett films is discussed in Chapter XV. 

Bartell and co-workers have made significant progress by combining electron diffraction studies from beams of molecular clusters with molecular dynamics simulations [14, 51, 52]. Due to their small volumes, deep supercoolings can be attained in cluster beams however, the temperature is not easily controlled. The rapid nucleation that ensues can produce new phases not observed in the bulk [14]. Despite the concern about the appropriateness of the classic model for small clusters, its application appears to be valid in several cases [51]. 

For bulk structural detemiination (see chapter B 1.9). the main teclmique used has been x-ray diffraction (XRD). Several other teclmiques are also available for more specialized applications, including electron diffraction (ED) for thin film structures and gas-phase molecules neutron diffraction (ND) and nuclear magnetic resonance (NMR) for magnetic studies (see chapter B1.12 and chapter B1.13) x-ray absorption fine structure (XAFS) for local structures in small or unstable samples and other spectroscopies to examine local structures in molecules. Electron microscopy also plays an important role, primarily tlirough unaging (see chapter B1.17). 

Electron diffraction studies provide valuable information about structures in the gas phase. Consequently, this method is important for chalcogen-nitrogen compounds that are liquids or gases at room temperature. The application of this technique has provided evidence for the monomeric structures of the 1,2,3,5-dithiadiazolyl radical [CEsCNSSN] (3.3) and the 1,3,2-dithiazolyl [CEsCSNSCCEs] (3.4), a... 

A New Electron Diffraction Technique, Potentially Applicable to Research in Catalysis L. H. Germer... 

The most extensive application which was made of the resonance curve was to the carbon-chlorine bond in phosgene and the chloroethylenes. In the electron-diffraction study of these substances2 the carbon-carbon and carbon-oxygen doublebond values 1.38 and 1.28 A. were assumed the question accordingly arises as to what effect the new double bond values would have on the carbon-... 

J. B. Pendry, Low Energy Electron Diffraction the Theory and Its Application to the Determination of Surface Structure, Academic Press, New York, 1974 S. Anderson and J. B. Pendry, J. Phys. C, 1980, 13, 3547 see also references in Further Reading. 

L. H. Germer and A. U. MacRae, A new low electron diffraction technique having possible applications to catalysis, The Robert A. Welch Foundation Research Bulletin, 1961, No. 11. 

In this section we will discuss perturbation methods suitable for high-energy electron diffraction. For simplicity, in this section we will be concerned with only periodic structures and a transmission diffraction geometry. In the context of electron diffraction theory, the perturbation method has been extensively used and developed. Applications have been made to take into account the effects of weak beams [44, 45] inelastic scattering [46] higher-order Laue zone diffraction [47] crystal structure determination [48] and crystal structure factors refinement [38, 49]. A formal mathematical expression for the first order partial derivatives of the scattering matrix has been derived by Speer et al. [50], and a formal second order perturbation theory has been developed by Peng [22,34],... 

The methods available for structure determination are surveyed. Those that are applicable to the gas phase, i.e. electron diffraction and rotational spectroscopy, are suitable mainly for small molecules. Data for the crystalline phase are usually relatively straightforward to obtain, but acquiring reliable structural data for silicon compounds as liquids or in solution by diffraction methods or liquid crystal NMR spectroscopy remains a challenge. 

Quantum Chemical Calculations, in Stereochemical Applications of Gas-Phase Electron Diffraction, I. Hargittai and M. Hargittai, eds., Part A, Chap. 9, p. 301-319, VCH, New York (1988). 

Schafer, L., J. D. Ewbank, K. Siam, N. S. Chiu, and H. L. Sellers. 1988a. Molecular Orbital Constrained Electron Diffraction (MOCED) Studies The Concerted Use of Electron Diffraction and Quantum Chemical Calculations, in Stereochemical Applications of Gas-Phase Electron Diffraction, Hargittai, I., and Hargittai, M., eds., Vol. A, Chap. 9, 301-320. New York, VCH Publisher. 

X-ray, neutron, and electron diffraction techniques are used to determine crystal structures and can thus be used for molecular structure determinations. Because of its high resolution and applicability to small and often weakly diffracting samples, x-ray crystallography and powder diffraction are by far the methods of choice for most structure determinations on crystalline compounds,... 

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