Structural Electron Crystallography

Dorset, Douglas L.

doi:10.1007/978-1-4757-6621-9

Cited by 279 publications

(375 citation statements)

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“…1 mm diameter sampling) with an electron diffraction camera, were used to seek these positions by Fourier methods (Vainshtein, 1964b), starting with heavier-atom coordinates from contemporary X-ray crystal structure analyses. Despite early criticisms of this work, it was demonstrated recently (Dorset, 1995) that true ab initio determinations are indeed possible from such experimental data, even though the rather low accelerating voltages used in early experiments unfortunately limited the accuracy of the intensity data and actually precluded the location of the lighter-atom positions.…”

Section: Introductionmentioning

confidence: 93%

“…First, a drop of dilute solution in benzene was evaporated on a carbon-film-covered electron microscope grid. This is a typical method for rapidly growing microcrystals of many organic compounds (Dorset, 1995). Sccond, the material was suspended in a nonwetting solvent such as ethanol and then sonicatcd to make a fine dispersion of the smallcr needles.…”

Section: Crystal Growthmentioning

confidence: 99%

“…The third and most useful method for crystal preparation was to orient the material on a layer of naphthalcnc, a procedure often used for polymer samples (Wittmann & Lotz, 1990;Dorset, 1995). A sheet of mica was cleaved with a razor blade and a drop of thc dilute benzene solution was evaporatcd on this surface to form a thin layer of the organic.…”

Section: Crystal Growthmentioning

confidence: 99%

“…Since the sampling diameter (several micrometres) is much smaller than the one used for recording oblique texture patterns with an electron diffraction camera (Vainshtein, 1964b), special care must be taken to ensure that the crystal quality is sufficient to provide meaningful diffraction intensities. There is, for example, always the problem of elastic crystal bending which sometimes frustrates the quantitative interpretation of patterns in the projection down the longest unit-cell axis of crystals most typically grown from solution (Cowley, 1961;Dorset, 1995). In some cases, epitaxic orientation on a substrate has eliminated this problem by nucleating a view of the crystal packing where the projection onto molecular planes (and also down a shorter unit-cell axis) can be readily accessed.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electron Crystallography of Small Organic Molecules: Criteria for Data Collection and Strategies for Structure Solution

Dorset¹,

McCourt²,

Li³

et al. 1998

J Appl Cryst

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By crystallization onto an organic substrate such as naphthalene, thin microcrystals of a small organic molecule, such as triphenylene, can be grown. These crystals are less perturbed by shear and erratic bend disorder than the samples produced by rapid growth from dilute solutions. Selected-area electron diffraction intensities are consistent from specimen to specimen, show the symmetry expected for the crystalline projection and, furthermore, correspond to the Fourier transform of the entire unit cell. However, undersampling of the three-dimensional reciprocal lattice by goniometry can frustrate structure determination if conventional direct methods are used. Nevertheless, the crystal structure may still be solved quite accurately by energy minimization.

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Section: Introductionmentioning

confidence: 93%

Section: Crystal Growthmentioning

confidence: 99%

Section: Crystal Growthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electron Crystallography of Small Organic Molecules: Criteria for Data Collection and Strategies for Structure Solution

Dorset¹,

McCourt²,

Li³

et al. 1998

J Appl Cryst

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show abstract

“…For example, they can efficiently diffract at crystals, exactly as normal waves do when they strike a diffraction grating. From the observed diffraction patterns, one can then deduce quantitative structural information such as lattice constants and symmetry [1][2][3][4]. When used with ultrahigh time resolution, they even allow one to map structural changes as those occurring in phase transitions [5,6].…”

Section: Introductionmentioning

confidence: 99%

Intramolecular electron diffraction in vibrationally resolvedK-shell photoionization of methane

et al. 2012

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Current techniques based on x-ray or electron diffraction are successfully employed for structure determination in condensed matter but are sometimes limited when applied to low density media such as the gas phase. Here we show that vibrationally resolved photoelectron spectroscopy based on x rays generated by third generation synchrotron light sources can be used to infer the structure of isolated molecules in a simple and efficient way. In particular, we show that vibrational ratios obtained from inner shell C 1s photoelectron spectroscopy of isolated methane molecules exhibit pronounced oscillations that are the fingerprints of electron diffraction by the surrounding atomic centers, thus providing the necessary information for the determination of the molecular geometry.

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Prospects for the direct electron crystallographic determination of zeolite structures

Dorset

McCourt

1997

Microsc. Res. Tech.

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Recently two successful zeolite structures based on experimental electron crystallographic data have been published. Diffraction and image data based on the silicate portion of the zeolite, mordenite, which are perturbed by dynamical (as well as secondary) scattering, have been simulated by a multiple‐beam dynamical scattering program. Structure analyses with these data show that the above claims are not unreasonable, given a high enough accelerating voltage for the electron beam. If, for example, 2.9 Å resolution micrographs are taken from a 120 Å thick crystal in a 200 or 400 kV electron microscope, the crystallographic phases found by image analysis (Fourier filtration) are accurate enough to be extended by the Sayre equation to the (atomic) resolution limit of the electron diffraction pattern (for example from a 105 Å thick crystal illuminated by a 1,200 kV electron source). The resultant potential map can be interpreted to find most of the atomic positions and the remaining ones will appear during the progress of a Fourier refinement. Microsc. Res. Tech. 36:212–223, 1997. © 1997 Wiley‐Liss, Inc.

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Structural Electron Crystallography

Cited by 279 publications

References 0 publications

Electron Crystallography of Small Organic Molecules: Criteria for Data Collection and Strategies for Structure Solution

Electron Crystallography of Small Organic Molecules: Criteria for Data Collection and Strategies for Structure Solution

Intramolecular electron diffraction in vibrationally resolvedK-shell photoionization of methane

Prospects for the direct electron crystallographic determination of zeolite structures

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