Considerations of the Transmission of a Small Electron Probe Through a TEM Foil and Its Relation to Characteristic X-Ray Spatial Resolution

1981 ◽  
Vol 39 ◽  
pp. 282-283
Author(s):  
D. Imeson ◽  
J. B. Vander Sande
Keyword(s):  
Electron Beam ◽  
Spatial Resolution ◽  
Incident Beam ◽  
Thin Foil ◽  
Lateral Spreading ◽  
X Ray ◽  
Thin Foils ◽  
Transmission Electron ◽  
Composition Variation ◽  
Composition Determination

It is well established that when an electron beam is incident upon a thin foil in the form of a focused probe, as in STEM, multiple scattering events in the sample cause considerable lateral spreading of the electron beam. The volume of material excited by the electron beam is therefore much greater than that volume defined by simple projection of the incident beam through the sample. In the application of the techniques of quantitative X-ray analysis in STEM to regions of composition variation with small spatial extent this point becomes of crucial importance, being the main determinant of the ability to map such composition changes, or even to detect them. It is the view of the authors that there exists some confusion over the nature of the beam spreading phenomenon in thin foils of crystalline material and the concept of spatial resolution of composition determination by characteristic X-ray emission. We intend here to clarify these concepts by discussing the meaning and use of the term “beam broadening” in analytical transmission electron microscopy.

High-spatial-resolution x-ray microanalysis: Comparison of experiment and incoherent scattering calculations

1993 ◽  
Vol 51 ◽  
pp. 590-591
Author(s):  
J. R. Michael ◽  
A. D. Romig
Keyword(s):  
Electron Beam ◽  
Spatial Resolution ◽  
Thin Foil ◽  
Coherent Scattering ◽  
Incoherent Scattering ◽  
Spherical Particles ◽  
X Ray ◽  
Thin Foils ◽  
Oriented Parallel ◽  
Beam Broadening

There have been many experimental efforts to measure the spatial resolution for x-ray microanalysis in the analytical electron microscope (AEM). There have been three commonly utilized specimen geometries in these experiments: 1) segregant at a grain boundary, 2) interphase boundaries oriented parallel to the electron beam, and most recently 3) spherical particles embedded at various depths in thin foils. The results of many of these experiments have been analyzed with a number of models for the broadening of the electron beam as it traverses the thin foil. These models are typically based on incoherent electron scattering, typical of Monte Carlo simulations. A vast majority of the published spatial resolution data support the incoherent scattering models as the best simulation of spatial resolution for x-ray microanalysis in the AEM. Recent experimental work using embedded particles to measure beam broadening has been used to support the coherent scattering model of beam broadening.

The spatial resolution of x-ray microanalysis in thin foils

1991 ◽  
Vol 49 ◽  
pp. 472-473
Author(s):  
D. B. Williams ◽  
J. R. Michael ◽  
J. I. Goldstein ◽  
A. D. Romig
Keyword(s):  
Spatial Resolution ◽  
Thin Foil ◽  
Beam Specimen ◽  
Beam Diameter ◽  
Worst Case ◽  
X Ray ◽  
Thin Foils ◽  
Elastic Scatter ◽  
Electron Beam Diameter ◽  
Beam Broadening

The spatial resolution of x-ray microanalysis in a thin foil is determined by the size of the beam-specimen interaction volume. This volume is a combination of the incident electron beam diameter (d) and the beam broadening (b) due to elastic scatter within the specimen. Definitions of spatial resolution have already been proposed on this basis but all present a worst case value for the resolution based on the dimensions of the beam emerging from the exit face of the foil.

scholarly journals Deformation Mechanisms and Fracture of Ni-Based Metallic Glasses

2016 ◽  
Vol 61 (2) ◽  
pp. 791-796 ◽  
Author(s):  
S. Lesz ◽  
S. Griner ◽  
R. Nowosielski
Keyword(s):  
Electron Microscope ◽  
Optical Microscopy ◽  
Metallic Glasses ◽  
Thin Foil ◽  
Tensile Tests ◽  
Deformation Mechanisms ◽  
X Ray ◽  
Fracture Surfaces ◽  
Thin Foils ◽  
Transmission Electron

Abstract The cracking of materials and fracture surface is of great practical and academic importance. Over the last few years the development of the fractography of crystalline alloys resulted in a useful tool for the prediction or failure analysis. Many attempts have been made to observe cracks using optical microscopy, X-ray topography and transmission electron microscopy (TEM). Of these techniques, the resolution of optical microscopy and X-ray topography is too poor. By contrast, the resolution of TEM is high enough for detailed information to be obtained. However, in order to apply TEM observations, a thin foil specimen must be prepared, and it is usually extremely difficult to prepare such a specimen from a pre-selected region containing a crack. In the present work, deformation mechanisms fracture surfaces of Ni-based metallic glass samples have been studied by specially designed experiments. In order to study the deformation mechanisms and fracture the Ni-based metallic glasses have been investigated in the tensile test. The structure and fracture surfaces after the decohesion process in tensile tests were observed using transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. The studies of structure were performed on thin foils. Moreover the investigated tape was subjected to a banding test. Then, the tape was straightened and the thin foil from the area of maximum strain was prepared. This thin foil sample was deformed before the TEM investigation to obtain local tears.

Spatial Resolution of X-ray Analysis with Solid and Thin Specimens

1971 ◽  
Vol 29 ◽  
pp. 54-55 ◽  
Author(s):  
John C. Russ
Keyword(s):  
Spatial Resolution ◽  
Elemental Analysis ◽  
Secondary Electron ◽  
Incident Beam ◽  
Image Point ◽  
X Ray ◽  
Resolution Image ◽  
Solid Specimen ◽  
Transmission Electron ◽  
Electron Microscopes

The attachment of xray spectrometers, both wavelength and energy dispersive, to both scanning and transmission electron microscopes has provided the microscopist with the possibility of obtaining elemental analysis of features in the specimen that he can observe in the image. However, the volume of the specimen that emits xrays is in all cases larger than the image point he can observe in the highest resolution image with the microscope, and so he must use judgement to determine just how large a region is being analyzed.With a solid specimen in the SEM the situation is much like the conventional microprobe. Figure 1 shows the typical drop-shaped capture volume many times larger than the incident beam, and much deeper than the secondary electron source.

Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

1977 ◽  
Vol 35 ◽  
pp. 328-329
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Thin Foil ◽  
Electron Excitation ◽  
Simple Approach ◽  
Foil Thickness ◽  
X Rays ◽  
X Ray ◽  
Hole Spectrum ◽  
Illumination System ◽  
Thin Foils ◽  
Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

Optimizing conditions for x-ray microchemical analysis in analytical electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 548-549 ◽  
Author(s):  
N. J. Zaluzec
Keyword(s):  
Solid Angle ◽  
Analytical Electron Microscopy ◽  
Incident Beam ◽  
Thin Foil ◽  
Experimental Conditions ◽  
X Ray ◽  
Microchemical Analysis ◽  
Analytical Electron ◽  
Image Position ◽  
Incident Beam Energy

The ultimate sensitivity of microchemical analysis using x-ray emission rests in selecting those experimental conditions which will maximize the measured peak-to-background (P/B) ratio. This paper presents the results of calculations aimed at determining the influence of incident beam energy, detector/specimen geometry and specimen composition on the P/B ratio for ideally thin samples (i.e., the effects of scattering and absorption are considered negligible). As such it is assumed that the complications resulting from system peaks, bremsstrahlung fluorescence, electron tails and specimen contamination have been eliminated and that one needs only to consider the physics of the generation/emission process.The number of characteristic x-ray photons (Ip) emitted from a thin foil of thickness dt into the solid angle dΩ is given by the well-known equation

Spatial resolution of X-ray microanalysis in thin foils

1978 ◽  
Vol 36 (1) ◽  
pp. 544-545
Author(s):  
R. Hutchings ◽  
I.P. Jones ◽  
M.H. Loretto ◽  
R.E. Smallman
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Beam Divergence ◽  
Inelastic Interaction ◽  
Specimen Thickness ◽  
High Current ◽  
Beam Spreading ◽  
X Ray ◽  
Thin Foils ◽  
Complex Calculation

There is increasing interest in X-ray microanalysis of thin specimens and the present paper attempts to define some of the factors which govern the spatial resolution of this type of microanalysis. One of these factors is the spreading of the electron probe as it is transmitted through the specimen. There will always be some beam-spreading with small electron probes, because of the inevitable beam divergence associated with small, high current probes; a lower limit to the spatial resolution is thus 2αst where 2αs is the beam divergence and t the specimen thickness.In addition there will of course be beam spreading caused by elastic and inelastic interaction between the electron beam and the specimen. The angle through which electrons are scattered by the various scattering processes can vary from zero to 180° and it is clearly a very complex calculation to determine the effective size of the beam as it propagates through the specimen.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Transmission electron microscope studies in special ceramics

1978 ◽  
Vol 36 (1) ◽  
pp. 268-269
Author(s):  
A. Zangvil ◽  
L.J. Gauckler ◽  
G. Schneider ◽  
M. Rühle
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Thin Foil ◽  
Limited Extent ◽  
Complex Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

Automatic analysis of Kikuchi diffraction patterns

1994 ◽  
Vol 52 ◽  
pp. 900-901
Author(s):  
H. Weiland ◽  
D. P. Field
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Relevant Information ◽  
Crystalline Materials ◽  
Large Size ◽  
Transmission Electron ◽  
New Type ◽  
Diffraction Patterns ◽  
Orientation Determination

Recent advances in the automatic indexing of backscatter Kikuchi diffraction patterns on the scanning electron microscope (SEM) has resulted in the development of a new type of microscopy. The ability to obtain statistically relevant information on the spatial distribution of crystallite orientations is giving rise to new insight into polycrystalline microstructures and their relation to materials properties. A limitation of the technique in the SEM is that the spatial resolution of the measurement is restricted by the relatively large size of the electron beam in relation to various microstructural features. Typically the spatial resolution in the SEM is limited to about half a micron or greater. Heavily worked structures exhibit microstructural features much finer than this and require resolution on the order of nanometers for accurate characterization. Transmission electron microscope (TEM) techniques offer sufficient resolution to investigate heavily worked crystalline materials.Crystal lattice orientation determination from Kikuchi diffraction patterns in the TEM (Figure 1) requires knowledge of the relative positions of at least three non-parallel Kikuchi line pairs in relation to the crystallite and the electron beam.

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