A comparison of calculated images generated by six modes of transmission electron microscopy

Engel, Andréas; Wiggins, J. W.; Woodruff, D. C.

doi:10.1063/1.1663659

Cited by 62 publications

(15 citation statements)

References 23 publications

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“…Recall that within the first 94 A much of the electron intensity is focused into the channeling peaks where it remains for at least 470 A. The small dependence on crystal thickness of the images is an advantage of STEM over CTEM, where phase-contrast reversals can complicate image interpretation (Engel et al, 1974). Values of the adatom signal, the background intensity, and the contrast for each image are listed in Table 1.…”

Section: Thickness Effects On Visibilitymentioning

confidence: 99%

“…Because image formation for crystalline specimens is a complex nonlinear process, simple analytical descriptions are inadequate. Interference effects can lead to significant misinterpretation of results (Engel, Wiggins & Woodruff, 1974). Numerically intensive simulations are necessary as a guide to the O 1988 International Union of Crystallography correct interpretation.…”

Section: Introductionmentioning

confidence: 99%

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Visibility of single heavy atoms on thin crystalline silicon in simulated annular dark-field STEM images

Loane¹,

Kirkland²,

Silcox³

1988

Acta Cryst Sect A

186

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The multislice method, pioneered by Cowley and Moodie, has recently been adapted to simulate annular dark-field scanning transmission electronmicroscope (ADF STEM) images. This paper presents a series of calculations using this new approach with experimental parameters appropriate for a VG-HB501 STEM to investigate the visibility of single heavy adatoms on thin crystalline silicon membranes. The tendency for electrons to channel along columns of atoms in crystals can greatly increase the intensity incident on an adatom on the exit surface, thereby increasing the adatom visibility. The simulations indicate that an adatom on the exit surface on a column of crystal atoms is up to three times as visible as an adatom on the entrance surface, and that the adatom remains highly visible as the crystal thickness is increased. Tilting the specimen or displacing the adatom from the column appears to lower the visibility of the adatom dramatically. These calculations suggest that, with the appropriate imaging conditions, a single gold adatom may be visible on at least 235 of (111) silicon.

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Section: Thickness Effects On Visibilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Visibility of single heavy atoms on thin crystalline silicon in simulated annular dark-field STEM images

Loane¹,

Kirkland²,

Silcox³

1988

Acta Cryst Sect A

186

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show abstract

“…The high contrast delivered by the dark-field detector system [15] can also be exploited in negative or positive stain microscopy [16]. Here the STEM yields clear single-shot images that are free from phase contrast fringes.…”

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confidence: 99%

Biological Scanning Transmission Electron Microscopy: Imaging and Single Molecule Mass Determination

Müller¹,

Engel²

2006

Chimia

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scanning transmission electron microscopes can both measure the mass of single protein complexes and take amazingly clear images thereof, offering a wide range of applications in structural biology. The principle of mass measurement is presented and discussed and the scope of scanning transmission electron microscopy is illustrated by selected examples. Keywords:Mass determination · scanning transmission electron microscopy · sTEM unstained proteins to be clearly visualised under low dose conditions. Each pixel of the digital image is a quantitative scattering experiment from which the mass of the irradiated volume can be calculated [9]. Thus, the mass of a single protein complex can be determined by integrating over all pixel values that lie within its boundary. The method is applicable to macromolecules of widely varying mass and form (reviewed in [10]). When combined with SDS-gel electrophoresis and, where available, sequence information, STEM mass measurements serve to define protein stoichiometry. Further, as electron energy loss spectroscopy [11][12] or energy dispersive X-ray spectroscopy [13] can be performed while imaging, the STEM also offers the possibility of determining the distribution of specific elements in protein complexes. Indeed the feasibility of mapping single atoms bound to protein molecules has recently been demonstrated [14].The high contrast delivered by the dark-field detector system [15] can also be exploited in negative or positive stain microscopy [16]. Here the STEM yields clear single-shot images that are free from phase contrast fringes. These images frequently provide information only otherwise visible after averaging several hundred projections recorded with a transmission electron microscope (TEM). They thus make it possible to document the presence of distinct protein conformations, information that would be lost by averaging techniques. Indeed, STEM images of both negatively stained [17] and unstained [18] protein complexes have been used to reconstruct their 3D structure.The few dedicated STEMs employed in biology today are invaluable. In particular, the coupling of image and mass gives them the power to answer questions not resolvable by ultracentrifugation or mass spectrometry. Here we discuss the use of the STEM both as an imaging tool and to measure mass, and examine the uncertainties to be expected in STEM mass data sets. The Importance and Versatility of STEM Mass MeasurementsWorldwide, only four laboratories routinely use dedicated STEMs to measure the mass of biological samples. Their facilities are open for external collaborations and the many papers in the literature containing STEM mass measurements document the importance of this rare technique to the scientific community. Although the precision of STEM cannot match that of the mass spectrometer, its capability to measure an enormously wide mass range, its independence from shape assumptions and the presence of an image make the STEM an invaluable tool.The methodology of mass spectrometry has develop...

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“…The initial scatter contrast images of single atoms and clusters by Crewe and coworkers [65], as well as image simulations [87] showed the clear signature characteristics of an incoherent image, a single unique focus for the atoms and a resolution that is approximately p 2 better than phase contrast imaging. Also the images demonstrated increased Z-contrast, i.e., a stronger contrast as function of Z, as expected, since high angle scattering approaches the cross section for unscreened Rutherford scattering, which is proportional to Z 2 .…”

Section: Phase Contrast Versus Scatter Contrastmentioning

confidence: 99%

“…In parallel with the applications to biology was an analysis of the image contrast mechanism in TEM and STEM [86][87][88]. The contrast mechanisms are explained in detail in several books, e.g., those of Reimer [89] and Spence [90].…”

Section: Reciprocitymentioning

confidence: 99%

Three-Dimensional Aberration-Corrected Scanning Transmission Electron Microscopy for Biology

Lupini¹,

Peckys²,

Jonge³

et al. 2007

Nanotechnology in Biology and Medicine

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A comparison of calculated images generated by six modes of transmission electron microscopy

Cited by 62 publications

References 23 publications

Visibility of single heavy atoms on thin crystalline silicon in simulated annular dark-field STEM images

Visibility of single heavy atoms on thin crystalline silicon in simulated annular dark-field STEM images

Biological Scanning Transmission Electron Microscopy: Imaging and Single Molecule Mass Determination

Three-Dimensional Aberration-Corrected Scanning Transmission Electron Microscopy for Biology

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