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  • Chemistry  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of dead-time corrections in EDS systems (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 12 (1983), S. 2-7 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Two common methods of applying dead-time corrections in EDS systems, both of which are carried out internally in the electronics, are examined. The Barnhart method shows serious discrepancies when making dead-time corrections and in certain cases no correction is made at all. The problem is associated with the reliance on the fast amplifier to count all x-rays collected by the detector. In practice, however, the fast amplifier does not always succeed in carrying out this function since x-rays with energies 〈 1500 eV may fall below its threshold level. The problems become worse when a formvar window is substituted for beryllium since a greater proportion of low energy x-rays can now reach the detector. The magnitude of the discrepancy is shown also to be a function of specimen and electron accelerating voltage. Similar experiments with an EDS system using the Covell method show that no such discrepancies arise.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300120103
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Quantitative light element analysis using an energy dispersive detector. 1-Dead time and the low-energy spectrum (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 13 (1984), S. 69-77 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A study of the low-energy region (below 1. 5 keV) of energy dispersive x-ray spectra has been carried out. Firstly, because some counting systems do not provide a reliable dead time correction, a new method of dealing with the problem is given. Next, the effects of different positioning of the energy discriminator within the analyser circuitry are discussed with reference to the consequences for light element analysis. Electronic noise counts can present a problem for analysis of x-rays of less than 300 eV and a straightforward method for noise removal is described. Finally, an unexpected artifact in the spectrum below 500 eV is identified; its size is related to the total number of counts in the spectrum and a practical method of dealing with it is demonstrated. Once the above factors have been taken into account a low energy spectrum is produced, consisting solely of characteristic x-ray lines and a true continuum background.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300130207
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  • 3
    Electronic Resource
    Electronic Resource
    Quantitative light element analysis using an energy-dispersive detector: 2For Part 1 see Ref. 4. - continuum removal and peak deconvolution (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 14 (1985), S. 8-15 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Techniques for analysing light elements by energy-dispersive spectrometry are discussed and a new approach is proposed. Firstly, a method for predicting the x-ray continuum level is developed. It is based on the use of a reference standard and, unlike other methods, is accurate below 1.5 ke V. When combined with methods for dealing with spectrum artefacts, this approach allows the calculation of background levels down to 0.1 ke V. Attention is then given to the problem of overlap, which is particularly important in light element analysis. Various methods for deconvolution of peaks are considered and a technique is adopted based on least-squares fitting of standard peak profiles. The effects of count statistics and computational accuracy on the final results are discussed. Some practical overlap situations are examined to discover the level of accuracy which can be expected.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300140104
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  • 4
    Electronic Resource
    Electronic Resource
    Quantitative light element analysis using an energy-dispersive detector: 3For Part 2. see Ref. 2. - practical assessment of accuracy and sensitivity (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 14 (1985), S. 139-148 
    Details
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A comparison has been made between light element (5 〈 Z 〈 11) analyses performed using energy-dispersive and wavelength-dispersive spectrometry. It is shown that, provided appropriate spectrum processing methods are adopted, the two sets of data agree to within 2-3%. Since there is every reason to believe the wavelength-dispersive measurements are accurate, this demonstrates the feasibility of carrying out quantitative light element analysis by the energy-dispersive technique. The minimum concentrations of carbon, nitrogen and oxygen which can be detected in selected matrices have been established and it is shown that sensitivities of better than 0.5 wt% are achievable if the electron probe voltage is carefully chosen.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/xrs.1300140308
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