scholarly journals Nanocrystal Thickness Information From Z-STEM: 3-D Imaging in One Shot

1999 ◽  
Vol 589 ◽  
Author(s):  
A.V. Kadavanich ◽  
T. Kippeny ◽  
M. Erwin ◽  
S. J. Rosenthal ◽  
S. J. Pennycook
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Semiconductor Nanocrystals ◽  
Relative Thickness ◽  
Atomic Column ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Individual ◽  
Z Contrast ◽  
D Model ◽  
Contrast Image

AbstractWe have applied Atomic Number Contrast Scanning Transmission Electron Microscopy (Z-Contrast STEM) towards the study of colloidal CdSe semiconductor nanocrystals embedded in MEH-PPV polymer films.For typical nanocrystal thicknesses, the image intensity is a monotonic function of thickness. Hence an atomic column-resolved image provides information both on the lateral shape of the nanocrystal, as well as the relative thickness of the individual columns.We show that the Z-Contrast image of a single CdSe nanocrystal is consistent with the predicted 3-D model derived from considering HRTEM images of several nanocrystals in different orientations. We further discuss the possibility of measuring absolute thicknesses of atomic columns if the crystal structure is known.

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

2009 ◽  
Vol 367 (1903) ◽  
pp. 3709-3733 ◽  
Author(s):  
S. J. Pennycook ◽  
M. F. Chisholm ◽  
A. R. Lupini ◽  
M. Varela ◽  
A. Y. Borisevich ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Single Atom ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Z Contrast ◽  
Contrast Image ◽  
Aberration Corrected

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.

Effect of niobium on the oxidation behavior of TiAl

2007 ◽  
Vol 22 (6) ◽  
pp. 1486-1490 ◽  
Author(s):  
Wei Lu ◽  
ChunLin Chen ◽  
LianLong He ◽  
YanJun Xi ◽  
FuHui Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Potential Effect ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Scanning Transmission ◽  
Nb Doping ◽  
Z Contrast ◽  
Contrast Image

Two TiO2layers formed in TiAl oxidation for 50 h at 900 °C were studied using scanning transmission electron microscopy. The main efforts were placed on the investigation of the distribution of niobium. It was found that Nb enriched in TiO2grains of mixture layer but did not exist in the outer TiO2layer. High-resolution electron microscopy (HREM) Z-contrast image revealed that Nb substitute for Ti site leading to Nb enrichment in TiO2grains of the mixture layer. The formation mechanism of the two TiO2layers and the potential effect of Nb doping in the mixture layer were also discussed.

Incoherent Imaging by Z-Contrast Stem: Towards 1Å Resolution

1994 ◽  
Vol 332 ◽  
Author(s):  
S. J. Pennycook ◽  
D. E. Jesson ◽  
A. J. Mcgibbon
Keyword(s):  
Phonon Scattering ◽  
Scanning Transmission Electron Microscope ◽  
Complex Materials ◽  
Intrinsic Resolution ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Detector Geometry ◽  
Incoherent Imaging ◽  
Z Contrast ◽  
Contrast Image

ABSTRACTBy averaging phase correlations between scattered electrons a high angle detector in the scanning transmission electron microscope (STEM) can provide an incoherent, Z-contrast image at atomic resolution. Phase coherence is effectively destroyed through a combination of detector geometry (transverse incoherence) and phonon scattering (longitudinal incoherence). Besides having a higher intrinsic resolution, incoherent imaging offers the possibility of robust reconstruction to higher resolutions, provided that some lower frequency information is present in the image. This should have value for complex materials and regions of complex atomic arrangements such as grain boundaries. Direct resolution of the GaAs sublattice with a 300kV is demonstrated.

Oxygen Bonding in Bismuth Layered Compounds SrBi2Ta2O9

2007 ◽  
Vol 997 ◽  
Author(s):  
Dong Su ◽  
Nan Jiang ◽  
Jianguo Wen ◽  
Jianshe Liu
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Local Density ◽  
Layered Compounds ◽  
Density Approximation ◽  
Electron Loss ◽  
Density Of State ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Fine Structures ◽  
Z Contrast

AbstractWith the help of the high resolution Z-contrast scanning transmission electron microscopy (STEM), the near edge fine structures of the electron loss spectroscopy (EELS) arises from different layers are investigated in SBT. The EELS spectra are interpreted by comparing with the calculation using linearnized augment plane wave (LAPW) method within the local density approximation (LDA). The oxygen bonding nature in different layers are discussed. In Bi2O2 layer, oxygen 2p state interacted with the Bi 6p state leads to a high t2g state in density of state while in SrTa2O7 layer, oxygen 2p state hybridized with Ta 5d and Sr 5d, which leads a higher eg state than t2g state.

scholarly journals Flexible STEM with Simultaneous Phase and Depth Contrast

2021 ◽  
pp. 1-12
Author(s):  
Shahar Seifer ◽  
Lothar Houben ◽  
Michael Elbaum
Keyword(s):  
System Integration ◽  
Scanning Transmission Electron Microscopy ◽  
Phase Contrast ◽  
Wide Field ◽  
Analog To Digital ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Differential Phase Contrast ◽  
Flexible Stem ◽  
Contrast Image

Recent advances in scanning transmission electron microscopy (STEM) have rekindled interest in multi-channel detectors and prompted the exploration of unconventional scan patterns. These emerging needs are not yet addressed by standard commercial hardware. The system described here incorporates a flexible scan generator that enables exploration of low-acceleration scan patterns, while data are recorded by a scalable eight-channel array of nonmultiplexed analog-to-digital converters. System integration with SerialEM provides a flexible route for automated acquisition protocols including tomography. Using a solid-state quadrant detector with additional annular rings, we explore the generation and detection of various STEM contrast modes. Through-focus bright-field scans relate to phase contrast, similarly to wide-field TEM. More strikingly, comparing images acquired from different off-axis detector elements reveals lateral shifts dependent on defocus. Compensation of this parallax effect leads to decomposition of integrated differential phase contrast (iDPC) to separable contributions relating to projected electric potential and to defocus. Thus, a single scan provides both a computationally refocused phase contrast image and a second image in which the signed intensity, bright or dark, represents the degree of defocus.

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