Atomic number correction in electron probe x-ray microanalysis of curved samples and particles

1984 ◽  
Vol 56 (14) ◽  
pp. 2798-2801 ◽  
Author(s):  
Andrzej A. Markowicz ◽  
Rene E. Van Grieken
Keyword(s):  
Atomic Number ◽  
Electron Probe ◽  
X Ray ◽  
Curved Samples

A new and versatile computer program for correcting EPMA data

1992 ◽  
Vol 50 (2) ◽  
pp. 1658-1659
Author(s):  
I Farthing ◽  
G Love ◽  
VD Scott ◽  
CT Walker
Keyword(s):  
Chemical Composition ◽  
Computer Program ◽  
Programming Language ◽  
Atomic Number ◽  
Processing Speed ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Epma Data ◽  
X Ray ◽  
X Ray Absorption

A new computer program has been developed to convert electron probe microanalysis data into accurate measurements of chemical composition. It is menu-based and designed to operate off-line using any IBM PC compatible computer. As shown in the flowchart, fig. 1, the architecture is modular and the programming language adopted is a compilable version of BASIC which possesses much of the processing speed associated with FORTRAN or C. Specimens containing up to fifteen elements, with 4 ≤ Z ≤ 96, can be handled and all the major x-ray lines (Kα, Kβ, Lα, L(β, Mα and Mβ) are available for analysis purposes.The procedure itself is based upon the classical ZAF approach in which corrections for atomic number (Z), x-ray absorption (A), characteristic fluorescence (Fl) and continuum fluorescence (F2) are treated independently. The factors dealing with fluorescence are essentially those of Reed (characteristic) and Springer (continuum) although both contain minor updates. However, the atomic number and absorption factors are the authors' own and the latter, developed from a quadrilateral representation of the x-ray distribution with depth in a solid, distinguishes this program from others.

Electron probe x-ray microanalysis with energy-dispersive x-ray spectrometry: The basics of x-ray spectrum interpretation

1994 ◽  
Vol 52 ◽  
pp. 376-377
Author(s):  
Dale E. Newbury
Keyword(s):  
Atomic Number ◽  
Electron Probe ◽  
Energy Dispersive ◽  
X Ray ◽  
Linear Dimensions ◽  
Specimen Volume ◽  
Spectrum Interpretation ◽  
The Rich ◽  
Source Of Information ◽  
Basic Level

Electron probe x-ray microanalysis (EPMA) with energy dispersive x-ray spectrometry (EDS) provides the capability for detecting elements with atomic number ≥ 4 (beryllium) from an excited specimen volume with linear dimensions of micrometers and a mass in the picogram range. To maximize the utility of EPMA/EDS, the analyst needs to understand the rich source of information that is potentially available in the x-ray spectrum. At its most basic level, interpretation of the spectrum consists of recognizing and identifying the various components of the spectrum as recorded by the EDS system: characteristic peaks, artifacts, and continuum background. While a modern EDS system is capable of making this interpretation in an automatic fashion, the careful analyst will always check the computer’s interpretation, which of course demands that the analyst be at least as "smart" as the computer! A systematic examination of spectra from pure elements or simple compounds is a good way to develop the necessary working knowledge.

Going Nondispersive

1998 ◽  
Vol 4 (6) ◽  
pp. 552-558
Author(s):  
Kurt F.J. Heinrich ◽  
Ray Fitzgerald ◽  
Klaus Keil
Keyword(s):  
Solid State ◽  
Energy Range ◽  
Atomic Number ◽  
Energy Resolution ◽  
Electron Probe ◽  
Emission Lines ◽  
Crystal Spectrometer ◽  
X Ray ◽  
State Detection ◽  
The One

The energy-dispersive Si(Li) X-ray spectrometer, introduced 30 years ago into electron probe mi-croanalysis (EPMA) by R. Fitzgerald et al., has profoundly affected the development of microanalysis. It offers many advantages over the wavelength-dispersive crystal spectrometer. It has no moving parts and covers the full energy range of interest in EPMA. There is no defocusing over large distances on the specimen, the efficiency of the device is high, varies slowly and continuously with atomic number, and can be predicted fairly accurately, and, most importantly, all emission lines are detected and can be observed simultaneously. The one remaining disadvantage of the Si(Li) spectrometer is its poorer energy resolution. Solid-state detection devices now under development promise to achieve resolution comparable to that of the crystal spectrometer.

Improvements in the electron probe forming capabilities and x-ray hole counts in the Philips TEM

1983 ◽  
Vol 41 ◽  
pp. 376-377
Author(s):  
Richard L. McConville
Keyword(s):  
Field Strength ◽  
Electron Probe ◽  
Spherical Aberration ◽  
Focal Length ◽  
Objective Lens ◽  
Parallel Beam ◽  
Tilt Axis ◽  
X Ray ◽  
Small Probe ◽  
Specimen Height

A second generation twin lens has been developed. This symmetrical lens with a wider bore, yet superior values of chromatic and spherical aberration for a given focal length, retains both eucentric ± 60° tilt movement and 20°x ray detector take-off angle at 90° to the tilt axis. Adjust able tilt axis height, as well as specimen height, now ensures almost invariant objective lens strengths for both TEM (parallel beam conditions) and STEM or nano probe (focused small probe) modes.These modes are selected through use of an auxiliary lens situ ated above the objective. When this lens is on the specimen is illuminated with a parallel beam of electrons, and when it is off the specimen is illuminated with a focused probe of dimensions governed by the excitation of the condenser 1 lens. Thus TEM/STEM operation is controlled by a lens which is independent of the objective lens field strength.

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.

Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

1984 ◽  
Vol 42 ◽  
pp. 576-577
Author(s):  
M.D. Ball ◽  
H. Lagace ◽  
M.C. Thornton
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Transmission Electron Microscope ◽  
Convenient Method ◽  
Flow Chart ◽  
X Ray ◽  
Intensity Measurements ◽  
Transmission Electron ◽  
Electron Intensity ◽  
Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

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