Microchemical Analysis of thin Metal Foils

1976 ◽  
Vol 34 ◽  
pp. 420-421 ◽  
Author(s):  
N. J. Zaluzec ◽  
H. L. Fraser
Keyword(s):  
Thin Metal ◽  
Specimen Thickness ◽  
Marked Variation ◽  
X Ray ◽  
Metal Foils ◽  
Elemental Concentrations ◽  
Microchemical Analysis

Several techniques have been developed for quantitative x-ray microanalysis of thin metal foils. These techniques usually provide relative elemental concentrations, and assume that for a “thin” homogeneous alloy of elements A and B, the ratio of intensity (I) of any two characteristic x-ray peaks (e.g.IAKα/IBKα) should be independent of specimen thickness. Recently, Fraser et al., conducted experiments using a highly ordered alloy (β-NiAl) to investigate this assumption, and indeed showed that in electron transparent regions of the foils there was a marked variation in the ratio of the Ka peaks of Ni and Al, respectively. The results given by Fraser et al., are summarized in Fig. 1.

Energy Dispersive X-Ray Measurements of thin Metal Foils

1976 ◽  
Vol 34 ◽  
pp. 426-427
Author(s):  
J. Bentley ◽  
E. A. Kenik
Keyword(s):  
Materials Science ◽  
Energy Dispersive Spectrometer ◽  
Thin Foil ◽  
Thin Metal ◽  
Energy Dispersive ◽  
Thin Specimen ◽  
X Ray ◽  
Metal Foils ◽  
Small Probe ◽  
Scanning Transmission

Instruments combining a 100 kV transmission electron microscope (TEM) with scanning transmission (STEM), secondary electron (SEM) and x-ray energy dispersive spectrometer (EDS) attachments to give analytical capabilities are becoming increasingly available and useful. Some typical applications in the field of materials science which make use of the small probe size and thin specimen geometry are the chemical analysis of small precipitates contained within a thin foil and the measurement of chemical concentration profiles near microstructural features such as grain boundaries, point defect clusters, dislocations, or precipitates. Quantitative x-ray analysis of bulk samples using EDS on a conventional SEM is reasonably well established, but much less work has been performed on thin metal foils using the higher accelerating voltages available in TEM based instruments.

STEM-EDS X-RAY MICROANALYSIS IN THIN METAL FOILS

1984 ◽  
Vol 45 (C2) ◽  
pp. C2-381-C2-386
Author(s):  
P. Doig ◽  
P. E.J. Flewitt
Keyword(s):  
Thin Metal ◽  
X Ray ◽  
Metal Foils

Digitally Controlled Multipoint STEM-EDX Microanalysis

1982 ◽  
Vol 40 ◽  
pp. 742-743
Author(s):  
E. D. Boyes
Keyword(s):  
Chemical Composition ◽  
Sample Preparation ◽  
Specimen Thickness ◽  
X Ray ◽  
Spatially Resolved ◽  
Peak Intensity ◽  
Microchemical Analysis ◽  
Digitally Controlled ◽  
Quantitative Analyses ◽  
Edx Microanalysis

Spatially resolved microchemical analysis of thin specimens by STEM-EDX can with advantage be performed using a series of quantitative analyses at a number of selected discrete points in a digitally controlled array.The conventional line traces in X-ray peak intensity are not necessarily a good indication of elemental distributions. Substantial errors can occur as a result of the need for spectrum processing, X-ray corrections and in the case of thin specimens due to variations in specimen thickness which may be associated with differential polishing of regions of different chemical composition during sample preparation. In some circumstances ratio line scanning1 may be an improvement.

X-ray determination of the thickness of thin metal foils

2013 ◽  
Vol 21 (3) ◽  
pp. 347-355 ◽  
Author(s):  
Robert C. Block ◽  
Jeffrey A. Geuther ◽  
Brian Methe ◽  
Devin P. Barry ◽  
Gregory Leinweber
Keyword(s):  
Thin Metal ◽  
X Ray ◽  
Metal Foils

Comments on “energy dispersive x-ray measurements of thin metal foils”

1977 ◽  
Vol 11 (4) ◽  
pp. 256-258 ◽  
Author(s):  
Nestor J. Zaluzec ◽  
John B. Woodhouse ◽  
Hamish L. Fraser
Keyword(s):  
Thin Metal ◽  
Energy Dispersive ◽  
X Ray ◽  
Metal Foils

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

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.

Problems in Thin-Film X-ray Quantification

1990 ◽  
Vol 48 (2) ◽  
pp. 458-459
Author(s):  
J N Chapman ◽  
W A P Nicholson
Keyword(s):  
Thin Film ◽  
Specimen Thickness ◽  
X Rays ◽  
Characteristic Peak ◽  
Local Composition ◽  
X Ray ◽  
Measured Ratio ◽  
Path Lengths ◽  
Composition Changes

Energy dispersive x-ray microanalysis (EDX) is widely used for the quantitative determination of local composition in thin film specimens. Extraction of quantitative data is usually accomplished by relating the ratio of the number of atoms of two species A and B in the volume excited by the electron beam (nA/nB) to the corresponding ratio of detected characteristic photons (NA/NB) through the use of a k-factor. This leads to an expression of the form nA/nB = kAB NA/NB where kAB is a measure of the relative efficiency with which x-rays are generated and detected from the two species.Errors in thin film x-ray quantification can arise from uncertainties in both NA/NB and kAB. In addition to the inevitable statistical errors, particularly severe problems arise in accurately determining the former if (i) mass loss occurs during spectrum acquisition so that the composition changes as irradiation proceeds, (ii) the characteristic peak from one of the minority components of interest is overlapped by the much larger peak from a majority component, (iii) the measured ratio varies significantly with specimen thickness as a result of electron channeling, or (iv) varying absorption corrections are required due to photons generated at different points having to traverse different path lengths through specimens of irregular and unknown topography on their way to the detector.

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