A Novel Diode Detector in a Scanning Transmission Microscope

1972 ◽  
Vol 30 ◽  
pp. 442-443
Author(s):  
C. S. Kim ◽  
T. E. Everhart
Keyword(s):  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
Semiconductor Diode ◽  
Objective Lens ◽  
Contrast Effects ◽  
Thin Sample ◽  
Transmission Electron ◽  
High Energy Electrons ◽  
Scanning Transmission ◽  
Pass Through

High-resolution in a scanning transmission electron microscope can be obtained using a condenser-objective lens. A suitable semiconductor diode is an efficient detector of high-energy electrons; an annular detector allows unscattered primary electrons or inelastically scattered electrons to pass through the hole, while elastically scattered electrons strike the diode, and are detected.Electrons passing through a thin sample may be elastically scattered through angles of many tens of milliradians, inelastically scattered with angular deflections of ∼ 1 mr, or not scattered at all. The inelastically scattered electrons do not depart significantly from the unscattered beam. Since the beam convergence angle at the sample is typically a few milliradians, the elastically scattered electrons can be collected using a detector with a hole positioned at the beam axis to allow the inelastically scattered electrons and the unscattered electrons to pass through. These electrons can be separated with an electron spectrometer to provide important contrast effects.

scholarly journals Controlling Radiolysis Chemistry on the Nanoscale in Liquid Cell Scanning Transmission Electron Microscopy

2021 ◽  
Author(s):  
Juhan Lee ◽  
Daniel Nicholls ◽  
Nigel Browning ◽  
B. Layla Mehdi
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
High Energy Electrons ◽  
Scanning Transmission ◽  
Liquid Cell

When high-energy electrons from a scanning transmission electron microscope (STEM) are incident on a liquid, the vast majority of the chemical reactions that are observed are induced by the radiolysis...

scholarly journals Sub-Ångstrom Resolution

2003 ◽  
Vol 11 (6) ◽  
pp. 3-7
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Electron Microscope ◽  
Light Microscope ◽  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
Significant Advance ◽  
Contrast Method ◽  
Transmission Electron ◽  
High Energy Electrons ◽  
Scanning Transmission ◽  
Z Contrast

Antoni van Leeuwenhoek showed the practical use of the light microscope in the 1600s after much effort to improve the quality of optical lenses. Pioneering microscopists such as Ernst Abbé, Hermann Ludwig Ferdinand von Helmholtz, Lord John Rayleigh, Carl Zeiss, and August Köhler then brought us to the brink of optimal performance of the light microscope approximately a century ago, Ernst Ruska and Max Knoll showed in the 1930s that high-energy electrons could be used in place of light, giving greatly improved resolution. In the 1970's Albert Crewe and co-workers developed the scanning transmission electron microscope (STEM) and used the Z-contrast method to improve resolution in the electron microscope by about a factor of two. The scanning probe (nonoptical) microscopes aside, there hasn't been a significant advance in spatial resolution since.

Description of a New High Resolution Scanning Transmission EM

1972 ◽  
Vol 30 ◽  
pp. 418-419
Author(s):  
Michael Beer ◽  
J. W. Wiggins ◽  
David Woodruff ◽  
Jon Zubin
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Energy Dispersive Spectrometer ◽  
Scanning Transmission Electron Microscope ◽  
Objective Lens ◽  
Condenser Lens ◽  
Transmission Electron ◽  
Pattern Size ◽  
Scanning Transmission ◽  
Under Construction

A high resolution scanning transmission electron microscope of the type developed by A. V. Crewe is under construction in this laboratory. The basic design is completed and construction is under way with completion expected by the end of this year.The optical column of the microscope will consist of a field emission electron source, an accelerating lens, condenser lens, objective lens, diffraction lens, an energy dispersive spectrometer, and three electron detectors. For any accelerating voltage the condenser lens function to provide a parallel beam at the entrance of the objective lens. The diffraction lens is weak and its current will be controlled by the objective lens current to give an electron diffraction pattern size which is independent of small changes in the objective lens current made to achieve focus at the specimen. The objective lens demagnifies the image of the field emission source so that its Gaussian size is small compared to the aberration limit.

Resolution in the Scanning Transmission Electron Microscope

1972 ◽  
Vol 30 ◽  
pp. 454-455
Author(s):  
M. G. R. Thomson
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Spherical Aberration ◽  
Signal To Noise Ratio ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Objective Lens ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The variation of contrast and signal to noise ratio with change in detector solid angle in the high resolution scanning transmission electron microscope was discussed in an earlier paper. In that paper the conclusions were that the most favourable conditions for the imaging of isolated single heavy atoms were, using the notation in figure 1, either bright field phase contrast with β0⋍0.5 α0, or dark field with an annular detector subtending an angle between ao and effectively π/2.The microscope is represented simply by the model illustrated in figure 1, and the objective lens is characterised by its coefficient of spherical aberration Cs. All the results for the Scanning Transmission Electron Microscope (STEM) may with care be applied to the Conventional Electron Microscope (CEM). The object atom is represented as detailed in reference 2, except that ϕ(θ) is taken to be the constant ϕ(0) to simplify the integration. This is reasonable for θ ≤ 0.1 θ0, where 60 is the screening angle.

Design of a new objective lens for an HB-501A STEM

1991 ◽  
Vol 49 ◽  
pp. 416-417
Author(s):  
Earl J. Kirkland ◽  
Robert J. Keyse
Keyword(s):  
High Resolution ◽  
Spherical Aberration ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Objective Lens ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
High Resolution Microscopy

An ultra-high resolution pole piece with a coefficient of spherical aberration Cs=0.7mm. was previously designed for a Vacuum Generators HB-501A Scanning Transmission Electron Microscope (STEM). This lens was used to produce bright field (BF) and annular dark field (ADF) images of (111) silicon with a lattice spacing of 1.92 Å. In this microscope the specimen must be loaded into the lens through the top bore (or exit bore, electrons traveling from the bottom to the top). Thus the top bore must be rather large to accommodate the specimen holder. Unfortunately, a large bore is not ideal for producing low aberrations. The old lens was thus highly asymmetrical, with an upper bore of 8.0mm. Even with this large upper bore it has not been possible to produce a tilting stage, which hampers high resolution microscopy.

High-Efficiency Three-Dimensional Visualization of Complex Microstructures via Multidimensional STEM Acquisition and Reconstruction

2020 ◽  
Vol 26 (2) ◽  
pp. 240-246 ◽  
Author(s):  
Kevin G. Field ◽  
Benjamin P. Eftink ◽  
Chad M. Parish ◽  
Stuart A. Maloy
Keyword(s):  
High Efficiency ◽  
3D Visualization ◽  
Accurate Determination ◽  
Three Dimensional ◽  
High Energy ◽  
Scanning Transmission Electron Microscope ◽  
Chromium Steel ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractComplex material systems in which microstructure and microchemistry are nonuniformly dispersed require three-dimensional (3D) rendering(s) to provide an accurate determination of the physio-chemical nature of the system. Current scanning transmission electron microscope (STEM)-based tomography techniques enable 3D visualization but can be time-consuming, so only select systems or regions are analyzed in this manner. Here, it is presented that through high-efficiency multidimensional STEM acquisition and reconstruction, complex point cloud-like microstructural features can quickly and effectively be reconstructed in 3D. The proposed set of techniques is demonstrated, analyzed, and verified for a high-chromium steel with heterogeneously situated features induced using high-energy neutron bombardment.

Aberration-Corrected STEM: the Present and the Future

2001 ◽  
Vol 7 (S2) ◽  
pp. 896-897
Author(s):  
O.L. Krivanek ◽  
N. Dellby ◽  
P.D. Nellist ◽  
P.E. Batson ◽  
A.R. Lupini
Keyword(s):  
Spherical Aberration ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Objective Lens ◽  
High Angle ◽  
Successful Operation ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Full Speed ◽  
Aberration Corrected

Surprising as it may seem, aberration correction for the scanning transmission electron microscope (STEM) is now a practical proposition. The first-ever commercial spherical aberration corrector for a STEM was delivered by Nion to IBM Research Center in June 2000, and other deliveries have taken place since or are imminent. At the same time, the development of corrector hardware and software is still proceeding at full speed, and our understanding of what are the most important factors for the successful operation of a corrector is deepening continuously.Fig. 1 shows two high-angle dark field (HADF) images of [110] Si obtained with the IBM VG HB501 STEM operating at 120 kV, about 2 weeks after we fitted a quadrupole-octupole corrector into it. Fig. 1(a) shows the best HADF image that could be obtained with the corrector's quadrupoles on but its octupoles off. Sample structures were captured down to about 2.5 Å detail, easily possible in a STEM with a high resolution objective lens with a spherical aberration coefficient (Cs) of 1.3 mm. Fig. 1(b) shows a HADF image obtained after the Cs-correcting octupoles were turned on and the corrector tuned up. The resolution has now improved to 1.36 Å. This is sufficient to resolve the correct separation of the closely-spaced Si columns.

Unique Features of a High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 404-405
Author(s):  
J. W. Wiggins ◽  
M. Beer ◽  
D. C. Woodruff ◽  
J. A. Zubin
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Transmission Electron Microscope ◽  
Heavy Atom ◽  
Scanning Transmission Electron Microscope ◽  
Objective Lens ◽  
Optical Parameters ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

A high resolution scanning transmission electron microscope has been constructed and is operating. The initial task of this instrument is to attempt the sequencing of DNA by heavy-atom specific staining. It is also suitable for many other biological investigations requiring high resolution, low contamination and minimum radiation damage.The basic optical parameters are: 20 to 100 KV acceleration potential, objective lens focal length of 1.0 mm. with Cs = 0.7 mm., and two additional lenses designated as condensor and diffraction lenses. The purpose of the condensor lens is to provide a parallel beam incident to the objective, and the diffraction lens produces an image of the back focal plane of the objective in the plane of an annular detector.

High-resolution scanning electron microscopy

1987 ◽  
Vol 45 ◽  
pp. 530-533
Author(s):  
T. Nagatani
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Field Emission ◽  
Scanning Transmission Electron Microscope ◽  
Objective Lens ◽  
Second Development ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Scanning Electron

Although the main development of scanning electron microscopy (SEM) has been accomplished mostly by the Cambridge group and it has not been changed so much for about two decades, it should be noted that there have been two important developments to pursuing high resolution of better than 1nm.Most notably, use of a field emission gun developed by Crewe et al for the scanning transmission electron microscope (STEM) to form a fine electron beam has been most effective in SEMs due to its high brightness and low energy spread. Thus, several models of field emission (FE) SEMs have been developed in the early ’70s and commercialized with a resolution of 2∼3nm at around 30kV.The second development is to use a highly excited objective lens. The specimen has to be set inside the pole-pieces (so-called “in-lens” type).

Sign in / Sign up

Export Citation Format

Share Document