Incoherent imaging of thin specimens using coherently scattered electrons

Jesson, D. E.; Pennycook, Stephen J.

doi:10.1098/rspa.1993.0060

Cited by 126 publications

(23 citation statements)

References 33 publications

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“…(7) stiil holds. the object function may show a non-linear thickness dependence (see for example Jesson and Pennycook, 1993). However, the phase-object approach taken above demonstrates the principles of how incoherent phase-contrast can be achieved.…”

Section: Incoherent Imaging From Coherent Interferencementioning

confidence: 97%

Probe and object function reconstruction in incoherent stem imaging

Nellist¹,

Pennycook²

1996

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Section: Incoherent Imaging From Coherent Interferencementioning

confidence: 97%

Probe and object function reconstruction in incoherent stem imaging

Nellist¹,

Pennycook²

1996

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“…Optical sectioning is now opposed by the tendency of the columns to channel the electrons. Beams incident near the optic axis couple efficiently into the 1 s Bloch state, which before aberration correction was the dominant contribution to the ADF image (Pennycook & Jesson 1990Jesson & Pennycook 1993, 1995Nellist & Pennycook 1999). After aberration correction, the outer beams passing through the outer regions of the objective aperture are now so far from the zone axis that they do not channel strongly and therefore still tend to come to a focus as if propagating in free space.…”

Section: New Possibilities With Aberration-corrected Scanning Transmimentioning

confidence: 99%

Aberration-corrected scanning transmission electron microscopy: from atomic imaging and analysis to solving energy problems

Pennycook

Chisholm

Lupini

et al. 2009

Phil. Trans. R. Soc. A.

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The new possibilities of aberration-corrected scanning transmission electron microscopy (STEM) extend far beyond the factor of 2 or more in lateral resolution that was the original motivation. The smaller probe also gives enhanced single atom sensitivity, both for imaging and for spectroscopy, enabling light elements to be detected in a Z-contrast image and giving much improved phase contrast imaging using the bright field detector with pixel-by-pixel correlation with the Z-contrast image. Furthermore, the increased probe-forming aperture brings significant depth sensitivity and the possibility of optical sectioning to extract information in three dimensions. This paper reviews these recent advances with reference to several applications of relevance to energy, the origin of the low-temperature catalytic activity of nanophase Au, the nucleation and growth of semiconducting nanowires, and the origin of the eight orders of magnitude increased ionic conductivity in oxide superlattices. Possible future directions of aberration-corrected STEM for solving energy problems are outlined.

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“…As explained by Jesson & Pennycook (1993), transverse coherence is broken primarily as a result of detector geometry. By considering two neighbouring atoms in the transverse plane they showed that, when integrating over an annular detector of sufficiently high inner angle v i , destructive interference effectively cancels out coherent scattering contributions.…”

Section: Incoherent Imaging In Stem: An Inverse Problemmentioning

confidence: 99%

“…Although primarily incoherent, Jesson & Pennycook (1995) showed that rather than representing each column as an array of independently vibrating atoms, scattering can be visualized in terms of an assembly of independent 'packets' of atoms. By retrieving the object function directly from acquired data, it may be possible to gain a greater understanding of effects such as partial coherence in the z-direction directly from the image data.…”

Section: Incoherent Imaging In Stem: An Inverse Problemmentioning

confidence: 99%

Crystal structure retrieval by maximum entropy analysis of atomic resolution incoherent images

McGibbon

Pennycook

Jesson

1999

Journal of Microscopy

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SummaryIn this paper, we discuss the application of the maximum entropy method to atomic resolution Z-contrast images acquired in a scanning transmission electron microscope. Zcontrast is an incoherent imaging technique, and can be described as a convolution between an object function (the real-space map of the columnar scattering cross-section to high angles) and a point spread function (the effective electron probe). As such, we show that the technique is ideally suited to maximum entropy analysis which can, given an electron probe distribution, retrieve the 'most likely' Z-contrast object function. Using both simulated and experimentally acquired data, we explore the capabilities of maximum entropy analysis when applied to atomic resolution Z-contrast images, drawing conclusions on both the range of applicability of the technique and the nature of the retrieved crystal structures. Ultimately, we show the way in which the combination of Z-contrast imaging with maximum entropy analysis can be used to yield important information on unexpected atomic structures.

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Incoherent imaging of thin specimens using coherently scattered electrons

Cited by 126 publications

References 33 publications

Probe and object function reconstruction in incoherent stem imaging

Probe and object function reconstruction in incoherent stem imaging

Aberration-corrected scanning transmission electron microscopy: from atomic imaging and analysis to solving energy problems

Crystal structure retrieval by maximum entropy analysis of atomic resolution incoherent images

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