Energy-filtered electron diffraction from amorphized solids in the dedicated scanning transmission electron microscope (STEM)¶

1996 ◽  
Vol 54 ◽  
pp. 702-703
Author(s):  
A. N. Sreeram ◽  
L.-C. Qin ◽  
A. J. Garratt-Reed ◽  
L. W. Hobbs
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Scanning Transmission Electron Microscope ◽  
Real Space ◽  
Distribution Functions ◽  
Space Distribution ◽  
Electron Diffraction Data ◽  
X Rays ◽  
Transmission Electron ◽  
Scanning Transmission

There is significant current interest in understanding the structure of aperiodic solids, such as originally crystalline material amorphized by ion implantation, impact or application of massive pressures, or deposited amorphous thin films, which occupy small volumes. Radially-averaged real-space distribution functions can be derived from diffraction data, the best of which come from thermal neutron diffraction, which inconveniently requires large volumes. Neutron data are collectable in reciprocal space out to q ≡ 2sin(Θ/2)/λ = 70 nm-1, where Θ is the scattering angle and λ the wavelength, or about twice as far as for X-rays, which also require large diffracting volumes. Electron diffraction is the only recourse for very small volumes because of the much stronger interaction of the electron, but spectra must be energy filtered to remove the large inelastic scattering component. Recently, it has been shown that useful electron diffraction data can be collected conveniently to at least q = 16 nm-1 in the VG HB5 dedicated 100-kV field-emission STEM. This contribution details our experiences with improved collection in the VG HB603 instrument operating at 250 kV.

On the Determination of Partial RDFs for Amorphous Materials

1993 ◽  
Vol 321 ◽  
Author(s):  
L. C. Qin ◽  
L. W. Hobbs
Keyword(s):  
Electron Diffraction ◽  
Diffraction Data ◽  
Amorphous Materials ◽  
Vitreous Silica ◽  
Scanning Transmission Electron Microscope ◽  
Distribution Functions ◽  
Electron Diffraction Data ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

ABSTRACTRadial distribution functions (RDFs) for vitreous silica (V-SiO2) have been obtained from energy-filtered electron diffraction data obtained in the HB5 scanning transmission electron Microscope. Results have been compared with those obtained from high-resolution neutron diffraction experiments, and are in good agreement within experimental errors. It was found to be impractical to obtain partial RDFs for this material from combined neutron, X-ray and electron diffraction data, because the similarities in characteristics of X-ray and electron scattering cause indeter-Minacies. A criterion equation has been given to determine feasibility.

scholarly journals SUePDF: a program to obtain quantitative pair distribution functions from electron diffraction data

2017 ◽  
Vol 50 (1) ◽  
pp. 304-312 ◽  
Author(s):  
Dung Trung Tran ◽  
Gunnar Svensson ◽  
Cheuk-Wai Tai
Keyword(s):  
Electron Diffraction ◽  
Electron Scattering ◽  
Diffraction Data ◽  
Amorphous Materials ◽  
Fourier Transforms ◽  
Distribution Functions ◽  
Electron Diffraction Data ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Pair Distribution Functions

SUePDFis a graphical user interface program written in MATLAB to achieve quantitative pair distribution functions (PDFs) from electron diffraction data. The program facilitates structural studies of amorphous materials and small nanoparticles using electron diffraction data from transmission electron microscopes. It is based on the physics of electron scattering as well as the total scattering methodology. A method of background modeling is introduced to treat the intensity tail of the direct beam, inelastic scattering and incoherent multiple scattering. Kinematical electron scattering intensity is scaled using the electron scattering factors. The PDFs obtained after Fourier transforms are normalized with respect to number density, nanoparticle form factor and the non-negativity of probability density.SUePDFis distributed as free software for academic users.

scholarly journals Serial protein crystallography in an electron microscope

2019 ◽  
Author(s):  
Robert Bücker ◽  
Pascal Hogan-Lamarre ◽  
Pedram Mehrabi ◽  
Eike C. Schulz ◽  
Lindsey A. Bultema ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Scanning Transmission Electron Microscope ◽  
Dose Fractionation ◽  
X Ray Crystallography ◽  
Minimal Sample ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Alternative Means ◽  
Occlusion Bodies

AbstractSerial X-ray crystallography at free-electron lasers allows to solve biomolecular structures from sub-micron-sized crystals. However, beam time at these facilities is scarce, and involved sample delivery techniques are required. On the other hand, rotation electron diffraction (MicroED) has shown great potential as an alternative means for protein nano-crystallography. Here, we present a method for serial electron diffraction of protein nanocrystals combining the benefits of both approaches. In a scanning transmission electron microscope, crystals randomly dispersed on a sample grid are automatically mapped, and a diffraction pattern at fixed orientation is recorded from each at a high acquisition rate. Dose fractionation ensures minimal radiation damage effects. We demonstrate the method by solving the structure of granulovirus occlusion bodies and lysozyme to resolutions of 1.55 Å and 1.80 Å, respectively. Our method promises to provide rapid structure determination for many classes of materials with minimal sample consumption, using readily available instrumentation.

Factors Affecting Spatial Resolution for Compositional Analysis in Stem

1984 ◽  
Vol 41 ◽  
Author(s):  
John B. Vander Sande ◽  
Anthony J. Garratt-Reed
Keyword(s):  
Spatial Resolution ◽  
Compositional Analysis ◽  
Scanning Transmission Electron Microscope ◽  
Minimum Detectable Concentration ◽  
X Rays ◽  
Factors Affecting ◽  
Transmission Electron ◽  
Probe Size ◽  
Scanning Transmission ◽  
Detectable Concentration

AbstractThis paper discusses the application of the scanning transmission electron microscope (STEM) to the detection of segregation at interfaces via the monitoring of X-rays generated when the incident electrons interact with the segregant. Issues of spatial resolution and minimum detectable concentration are discussed. Specific examples, emphasizing the importance of probe size, sample thickness, and sample orientation, are presented.

STRUCTURE DETERMINATION OF THE Ge(111)-(3×1)Ag SURFACE RECONSTRUCTION

1999 ◽  
Vol 06 (06) ◽  
pp. 1061-1065 ◽  
Author(s):  
D. GROZEA ◽  
E. BENGU ◽  
C. COLLAZO-DAVILA ◽  
L. D. MARKS
Keyword(s):  
Electron Diffraction ◽  
Surface Reconstruction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Heavy Atom ◽  
Direct Methods ◽  
Electron Diffraction Data ◽  
Transmission Electron ◽  
First Time

For the first time, during the investigation of the Ag submonolayer on the Ge(111) system, large, independent domains of the Ge (111)-(3×1) Ag phase were imaged and investigated. Previous studies have reported it only as small insets between Ge (111)-(4×4) Ag and Ge (111)- c (2×8) domains. The transmission electron diffraction data were analyzed using a Direct Methods approach and "heavy-atom holography," with the result of an atomic model of the structure similar to that of Ge (111)-(3×1) Ag .

Identification of site-specific isotopic labels by vibrational spectroscopy in the electron microscope

Science ◽  
2019 ◽  
Vol 363 (6426) ◽  
pp. 525-528 ◽  
Author(s):  
Jordan A. Hachtel ◽  
Jingsong Huang ◽  
Ilja Popovs ◽  
Santa Jansone-Popova ◽  
Jong K. Keum ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Spatial Resolution ◽  
Theoretical Calculations ◽  
Scanning Transmission Electron Microscope ◽  
Real Space ◽  
Site Specific ◽  
Spatially Resolved ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Isotopic Labels

The identification of isotopic labels by conventional macroscopic techniques lacks spatial resolution and requires relatively large quantities of material for measurements. We recorded the vibrational spectra of an α amino acid, l-alanine, with damage-free “aloof” electron energy-loss spectroscopy in a scanning transmission electron microscope to directly resolve carbon-site–specific isotopic labels in real space with nanoscale spatial resolution. An isotopic red shift of 4.8 ± 0.4 milli–electron volts in C–O asymmetric stretching modes was observed for 13C-labeled l-alanine at the carboxylate carbon site, which was confirmed by macroscopic infrared spectroscopy and theoretical calculations. The accurate measurement of this shift opens the door to nondestructive, site-specific, spatially resolved identification of isotopically labeled molecules with the electron microscope.

John Maxwell Cowley 1923 - 2004

2006 ◽  
Vol 17 (2) ◽  
pp. 227
Author(s):  
A. F. Moodie ◽  
J. C. H. Spence
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Electron Scattering ◽  
Scanning Transmission Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Dynamical Theory ◽  
X Rays ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Scanning Transmission

John Cowley contributed significantly to all of the fields that relate to electron diffraction and electron microscopy, and helped to found not a few of them. His name is associated in particular with n-beam dynamical theory, high-resolution electron microscopy, scanning transmission electron microscopy, instrumental design, and the application of the techniques of electron scattering to structure analysis. His experimental work was not, however, confined to the scattering of electrons: to take but one instance, his seminal work on the theory of short-range order was stimulated initially by his experiments using X-rays, and it was only later that he extended the technique to include electron diffraction. Finally, to all those who practise the techniques of scattering electrons, X-rays, or neutrons in the study of solids, liquids or gases, his book Diffraction Physics remains not only eminently readable but authoritative.

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