Interpretation of the Atomic Surface Structure of Ag2O on (111) Au thin films

1983 ◽  
Vol 31 ◽  
Author(s):  
William Krakow
Keyword(s):  
Surface Structure ◽  
Image Features ◽  
Electron Microscope Investigation ◽  
Resolution Electron ◽  
Atomic Surface ◽  
High Resolution Electron Microscope ◽  
Au Thin Films ◽  
Diffraction Patterns ◽  
Digital Frame ◽  
Image Simulations

ABSTRACTA high resolution electron microscope investigation of the residual oxidized silver of a few monolayers thickness on the surface of (111) Au films has shown that a reconstructed (2×1) surface structure occurs for (110) oriented Ag2O and can be observed at atomic resolution levels. Image enhancement via a digital frame store processor has revealed improved images which have then been compared to computer simulated diffraction patterns and images of the Ag2O surface. Several iterations of surface structure models and image simulations reveal that the (2×1) reconstruction is consistent with a missing row model. The atomic arrangements of these rows often undergo a translation along the direction of the row to produce cusp like image features. It has also been possible to observe the effect of contraction of the underlying layer which can produce diagonal contrast lines in the images. These features often vary rapidly over lateral distances of a few tens of angstroms and give an indication of the surface topography and the degree ordering of the surface.

The Direct Observation of Atomic Surface Structure and Inclined Planar Defects in Au(111) Films

1981 ◽  
Vol 10 ◽  
Author(s):  
William Krakow
Keyword(s):  
Single Atom ◽  
Bottom Surface ◽  
Stacking Sequence ◽  
Planar Defects ◽  
Resolution Electron ◽  
Atomic Surface ◽  
High Resolution Electron Microscope ◽  
Diffraction Effects ◽  
First Time ◽  
Image Simulations

With a high resolution electron microscope it is possible to image directly the atomic surface lattice of vapor-deposited Au(111) films. The contrast of the surface atoms can be either black or white relative to the background which is characteristic of close-packed planes of atoms in the stacking sequence ABCABC.... An analysis of these images was performed using multislice dynamical diffraction computations of 256 × 256 = 65 536 reciprocal space points and subsequent image simulations. The effects of top and bottom surface roughness, different termination layers and the contrast compared with single-atom imaging are considered.The identification of atomic structure detail at incoherent double-position boundaries in these (111) films was also achieved. Surface layer terminations, variations in the choice of every third matching plane and the possibility that twinning planes produce boundaries with jogs were investigated. Multislice computer programs were designed to calculate the diffraction effects from these inclined boundaries using two-dimensional fast Fourier transform and shift techniques of the projected potential. This is the first time that inclined planar defects have been analyzed in this manner.

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

High-resolution electron microscopy of Cu2O surfaces

1986 ◽  
Vol 44 ◽  
pp. 396-397
Author(s):  
V. Castano ◽  
W. Krakow
Keyword(s):  
High Resolution ◽  
Natural Extension ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Initial Oxidation ◽  
System A ◽  
Resolution Electron ◽  
Surface Reconstructions ◽  
Atomic Surface ◽  
Au Thin Films

In non-UHV microscope environments atomic surface structure has been observed for flat-on for various orientations of Au thin films and edge-on for columns of atoms in small particles. The problem of oxidation of surfaces has only recently been reported from the point of view of high resolution microscopy revealing surface reconstructions for the Ag2O system. A natural extension of these initial oxidation studies is to explore other materials areas which are technologically more significant such as that of Cu2O, which will now be described.

The ultrastructure of coccoliths from the marine alga Emiliania huxleyi (Lohmann) Hay and Mohler: an ultra-high resolution electron microscope study

1983 ◽  
Vol 219 (1215) ◽  
pp. 111-117 ◽  
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Emiliania Huxleyi ◽  
Growth Patterns ◽  
Lattice Image ◽  
Nucleation Sites ◽  
Resolution Electron ◽  
Lattice Images ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns

The calcite coccoliths from the alga Emiliania huxleyi (Lohmann) Hay and Mohler have been studied by ultra-high resolution electron microscopy. This paper describes the two different types of structure observed, one in the upper elements, the other in the basal plate, or lower element. The former consisted of small, microdomain structures of 300-500 Å (1 Å = 10 -10 m) in length with no strong orientation. At places along these elements, and particularly in the junction between stem and head pieces, triangular patterns of lattice fringes were observed indicating multiple nucleation sites in the structure. In contrast, the lower element consisted of a very thin single crystalline sheet of calcite which could be resolved into a two dimensional lattice image, shown by a computer program that is capable of simulating electron diffraction patterns and lattice images to be a [421] zone of calcite. A possible mechanism for these growth patterns in the formation of coccoliths is discussed, together with the relevance of such mechanisms to biomineralization generally.

Dynamic TEM Observation on Oxide Glass Materials

1990 ◽  
Vol 183 ◽  
Author(s):  
Sumio Iijima
Keyword(s):  
Electron Beam Irradiation ◽  
Amorphous Film ◽  
Oxide Glass ◽  
Model Structure ◽  
Resolution Electron ◽  
Atom Migration ◽  
Intense Electron Beam ◽  
High Resolution Electron Microscope ◽  
Intense Electron ◽  
Image Simulations

AbstractIntensity fluctuation in high resolution electron microscope (HREM) images of amorphous Tl-Ba-Ca-Cu-O oxide films is observed. The fluctuation with a frequency of few tens of Hertz and an amplitude of about 0.3nm, occurs under an intense electron beam irradiation. It is shown experimentally that atom migration in the films is responsible for the fluctuations. The result is also supported by computer image simulations on a model structure for amorphous film.

scholarly journals Electron Microscopy for Atomic/Electronic Structure of Quasicrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C1193-C1193
Author(s):  
Eiji Abe
Keyword(s):  
Electron Microscopy ◽  
Electronic Structure ◽  
Scanning Transmission Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Aperiodic Order ◽  
Scanning Transmission ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Key Questions

As stated with special emphasis in the Noble Lecture by Dr. Shechtman, the quasicrystal discovery is definitely the victory of electron microscopy – the first icosahedral stereogram was constructed by a series of electron diffraction patterns from a tiny quasicrystalline grain, and the following high-resolution electron microscope images indeed confirmed a unique aperiodic order that can never be consistent with twinning of normal crystals. Almost thirty years after these early electron microscopy studies, we are now in the era of aberration-corrected electron microscopy which realizes a remarkable resolution beyond an Ångstrom scale [1, 2]. In the talk, I will describe the local atomic/electronic structure of quasicrystals using state-of-the-art scanning transmission electron microscopy, providing several striking insights that may lead to the answers for the longstanding key questions; "Where are the atoms? And why do quasicrystals form?"

Interfacial structure and interfacial reactions at the MgO/Al2O3 interface

1991 ◽  
Vol 49 ◽  
pp. 696-697
Author(s):  
D. X. Li ◽  
P. Pirouz ◽  
A. H. Heuer ◽  
S. Yadavalli ◽  
C. P. Flynn
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Molecular Beam ◽  
Interfacial Structure ◽  
Cross Sectional ◽  
Resolution Electron ◽  
High Resolution Electron Microscope ◽  
Electron Microscope Image ◽  
Image Simulations ◽  
Standard Techniques

MgO films were deposited on the (sample A), (0001)Al2O3 (sample B), and the (sample C) planes of sapphire by Molecular Beam Epitaxy (MBE). Cross-sectional UREM specimens were prepared using standard techniques and examined in a top-entry JEOL 4000FX high resolution electron microscope. Image simulations were performed using the SHRLI programs developed by O'Keefe.

Interfacial Structures in the Nb/MgO/Nb/Al2O3 Superlattice

1991 ◽  
Vol 49 ◽  
pp. 960-961
Author(s):  
D. X. Li ◽  
P. Pirouz ◽  
A. H. Heuer ◽  
S. Yadavalli ◽  
C. P. Flynn
Keyword(s):  
Ion Beam ◽  
Mechanical Grinding ◽  
Cross Sectional ◽  
Mbe Growth ◽  
Resolution Electron ◽  
Interfacial Structures ◽  
High Resolution Electron Microscope ◽  
Point To Point ◽  
Image Simulations ◽  
Standard Techniques

Nb/MgO/Nb/Al2O3 superlattices were prepared by MBE growth of Nb and MgO films on a (012)Al2O3 sapphire substrate. Cross sectional HREM specimens were prepared using standard techniques involving mechanical grinding to a thickness of 0.13 mm, dimpling to a thickness of 20 μm and ion beam milling at 6 kV. The samples were subsequently examined in a top-entry JEOL 4000EX high resolution electron microscope with a point-to-point resolution of ∼0.19 nm. Image simulations were performed using the SHRLI programs developed by O'Keefe.

Computer Modeling of High Resolution Electron Microscope Images Using 65,536 Beams

1980 ◽  
Vol 38 ◽  
pp. 178-179
Author(s):  
William Krakow
Keyword(s):  
Strain Field ◽  
Dynamical Theory ◽  
Sample Thickness ◽  
Computational Time ◽  
Scattering Approximation ◽  
Resolution Electron ◽  
Interstitial Defects ◽  
Microscope Images ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns

A system of computer programs which calculates both diffraction patterns and images of generalized objects using the kinematical scattering approximation has now been extended to include multislice dynamical theory. Calculations of this type have been obtained by other authors for interstitial defects where several approximations were necessary to save computational time such as considering the defect strain field to be confined to one slice or reducing the number of beams and sample thickness (e.g. 3999 beams at 7 min./slice).

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