Standardless Analysis

Wernisch, J.; Röhrbacher, Kurt

doi:10.1007/978-3-7091-7506-4_41

Cited by 6 publications

(8 citation statements)

References 20 publications

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“…This calculation is subject to errors, for example, in fluorescence yield or window absorption, which cancel out if standards are used. These errors have been well described by Pouchou (1994) and later by Newbury (1998), and the theory which follows draws upon their work, as well as the more general publications of Labar (1998), and Wernisch and Röhrbacher (1998), and the textbook by Reed (1993). In the reverse direction, it may be that the theory of spectrum simulation can contribute to the technique of standardless analysis, and we return to this subject in the discussion.…”

Section: Characteristic Line Intensitymentioning

confidence: 77%

Improved X-ray Spectrum Simulation for Electron Microprobe Analysis

2001

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The accurate calculation of characteristic peak intensity is essential for interpreting X-ray spectra in electron microprobe analysis. Conventionally, the measured intensity from a standard of known composition is used as a reference to simplify the calculation. However, if no such standard is available, then all factors influencing X-ray generation and X-ray detection efficiency must be included. If the intensity and energy distribution of the background radiation can also be calculated, the investigator can simulate an entire spectrum from an assumed composition, gaining powerful benefits in setting up an experiment and in confirming the results. The study presented here demonstrates a fast method of spectrum simulation, suitable for energydispersive spectroscopy (EDS), and assesses the accuracy using 309 spectra from samples of known composition. These include K, L, and M lines from elements of atomic number 6–92, excited by beam energies in the range of 5–30 keV. The RMS error between 360 measured and calculated peak intensities was found to be 7.1%. Central to the method is the use of the ratio of peak intensity/total background intensity, which allows spectra to be compared from instruments of differing collection efficiency, thereby easing the collection of data over a wide range of conditions.

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Section: Characteristic Line Intensitymentioning

confidence: 77%

Improved X-ray Spectrum Simulation for Electron Microprobe Analysis

2001

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“…The accuracy of so-called standardless analysis has been repeatedly discussed at EMAS workshops~Pouchou, 1994;Wernisch & Röhrbacher, 1998;Joy, 2002!. is applied to determine the concentration of chemical elements in a microscopic volume of a specimen.…”

Section: Introductionmentioning

confidence: 99%

“…A long-term goal of X-ray microanalysis is to calculate the concentrations without the additional need to measure spectra from standard specimens. The accuracy of so-called standardless analysis has been repeatedly discussed at EMAS workshops~Pouchou, 1994;Wernisch & Röhrbacher, 1998;Joy, 2002!. However, little attention has been paid to the spectrometer efficiency, which is the critical factor relating the counts measured by the EDS to the number of photons emitted toward the detector entrance window.…”

Section: Introductionmentioning

confidence: 99%

The Determination of the Efficiency of Energy Dispersive X-Ray Spectrometers by a New Reference Material

et al. 2006

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A calibration procedure for the detection efficiency of energy dispersive X-ray spectrometers (EDS) used in combination with scanning electron microscopy (SEM) for standardless electron probe microanalysis (EPMA) is presented. The procedure is based on the comparison of X-ray spectra from a reference material (RM) measured with the EDS to be calibrated and a reference EDS. The RM is certified by the line intensities in the X-ray spectrum recorded with a reference EDS and by its composition. The calibration of the reference EDS is performed using synchrotron radiation at the radiometry laboratory of the Physikalisch-Technische Bundesanstalt. Measurement of RM spectra and comparison of the specified line intensities enables a rapid efficiency calibration on most SEMs. The article reports on studies to prepare such a RM and on EDS calibration and proposes a methodology that could be implemented in current spectrometer software to enable the calibration with a minimum of operator assistance.

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“…Examination of the errors in standarless procedure reveals that the sources of the most significant errors are the atomic parameters. One of the main atomic parameters is the ionization cross section [1][2][3][4]. For this parameter, the common practice is to use semi-empirical formulas, which are affected by differences up to 40%.…”

mentioning

confidence: 99%

“…-Secondly, an absolute quantification procedure requires the accurate knowledge of atomic parameters that describe the electron interaction and the X-ray emission, such as the ionization cross section, mass absorption coefficient, fluorescent yields, Coster-Kronig transition and the relative transition probability (by using standards in quantitative microanalysis, many of these atomic parameters are canceled or do not need to be known accurately).-Thirdly, an absolute quantification procedure needs accurate determination of the detector efficiency. Although the long term stability of WDS instrument has been improved considerably, and standarless procedures with WDS instruments have been developed [3,5], standarless analysis remains mainly the method of EDS systems [1][2][3][4] Apart from uncertainty in measurement, sources of errors in standarless procedure are principally the result from the atomic parameters and the detector efficiency. Nowadays, the accuracy in description of X-ray depth distribution is largely superior than the two previous points [4,8].…”

mentioning

confidence: 99%

Capability and Uncertainty of Standardless Procedures for Quantitative Electron Probe X-ray Microanalysis

Merlet

2003

Microsc Microanal

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Electron probe microanalysis (EPMA) has become a well established technique for determining compositions of bulk and multilayer samples. Quantification is traditionally based on the use of standards and many uncertainties, resulting of the experimental conditions, the atomic data and the physical model describing the X-ray emission, can be canceled. Depending of the instrument, the operator experience and the nature of the sample, the uncertainty in the results by the use of standards can be expected to be less than 2%, even when mass absorption coefficient is very large. Unfortunately, measurements on many standards are time consuming and require the appropriate standard for the corresponding element. As a solution, standardless procedure [1-5] is an elegant way to overcome these obstacles. This method attempts to remove the need of standardization through calculation of pure element intensities. Two standardless procedures are largely used. The first one, based on absolute calculations, takes into account all aspects of X-ray generation, propagation, and detection, and the second one, based on mathematical fits, makes use of measured intensities from a limited set of pure standards. Since standardless procedures imply a decrease in accuracy, the aim of this paper is to evaluate the capability and the uncertainty of standardless analysis based on absolute quantification procedure, putting the emphasis on fundamental aspects.

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Standardless Analysis

Cited by 6 publications

References 20 publications

Improved X-ray Spectrum Simulation for Electron Microprobe Analysis

Improved X-ray Spectrum Simulation for Electron Microprobe Analysis

The Determination of the Efficiency of Energy Dispersive X-Ray Spectrometers by a New Reference Material

Capability and Uncertainty of Standardless Procedures for Quantitative Electron Probe X-ray Microanalysis

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