X-Ray Mass Absorption Coefficients: Measurements and Uses in the Quantitative Diffraction Analysis of Pyrite in Coals

1989 ◽  
Vol 33 ◽  
pp. 475-483 ◽  
Author(s):  
David L. Wertz ◽  
Charles B. Smithhart ◽  
Stacey L. Wertz
Keyword(s):  
Absorption Coefficient ◽  
Diffraction Method ◽  
Solid Material ◽  
Diffraction Peak ◽  
Powdered Sample ◽  
Reflection Method ◽  
Absorption Coefficients ◽  
X Ray ◽  
Mass Absorption ◽  
Crystalline Substrate

The mass absorption coefficient (μ) of a weakly absorbing solid material may be measured by either the transmission or the reflection method. The latter typically employs a crystalline substrate and the diffraction method, measuring the transmission of the diffraction peak(s) of the substrate through the analyte. Compressing or compacting a powdered sample is not required when the reflection method is used.

Measurement of Mass Absorption Coefficients Using Compton-Scattered Cu Radiation in X-ray Diffraction Analysis

1990 ◽  
Vol 34 ◽  
pp. 325-335 ◽  
Author(s):  
Steve J. Chipera ◽  
David L. Bish
Keyword(s):  
Chemical Composition ◽  
Solid State ◽  
Absorption Coefficient ◽  
Mass Absorption Coefficient ◽  
X Rays ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
Solid State Detector ◽  
X Ray ◽  
Mass Absorption

AbstractThe mass absorption coefficient is a useful parameter for quantitative characterization of materials. If the chemical composition of a sample is known, the mass absorption coefficient can be calculated directly. However, the mass absorption coefficient must be determined empirically if the chemical composition is unknown. Traditional methods for determining the mass absorption coefficient involve measuring the transmission of monochromatic X-rays through a sample of known thickness and density. Reynolds (1963,1967), however, proposed a method for determining the mass absorption coefficient by measuring the Compton or inelastic X-ray scattering from a sample using Mo radiation on an X-ray fluorescence spectrometer (XRF). With the recent advances in solid-state detectors/electronics for use with conventional powder diffractometers, it is now possible to readily determine mass absorption coefficients during routine X-ray diffraction (XRD) analyses.Using Cu Kα radiation and Reynolds’ method on a Siemens D-500 diffractometer fitted with a Kevex Si(Li) solid-state detector, we have measured the mass absorption coefficients of a suite of minerals and pure chemical compounds ranging in μ/ρ from graphite to Fe-metal (μ/ρ = 4.6-308 using Cu Kα radiation) to ±4.0% (lσ). The relationship between the known mass absorption coefficient and the inverse count rate is linear with a correlation coefficient of 0.997. Using mass absorption coefficients, phase abundances can be determined during quantitative XRD analysis without requiring the use of an internal standard, even when an amorphous component is present.

Mass Absorption Corrected X-Ray Powder Diffractograms. Part 1: Measuring Pyrite in Powdered Coals

1990 ◽  
Vol 5 (1) ◽  
pp. 44-47 ◽  
Author(s):  
David L. Wertz
Keyword(s):  
Absorption Coefficient ◽  
Limit Of Detection ◽  
Diffraction Peak ◽  
Mass Absorption Coefficient ◽  
Measured Intensity ◽  
X Ray ◽  
Mass Absorption ◽  
Powdered Coal ◽  
Analysis Protocol

AbstractAn X-ray analysis method has been developed for the quantitative analysis of pyrite (FeS2) in coals and lignites. Requiring neither the use of external or internal references, the method linearly relates diffraction peak area in the absorption corrected X-ray diffractogram obtained from the finely powdered coal to the pyrite abundance. The [311] diffraction peak of pyrite (FeS2) has been used to develop the analysis protocol. The Argonne premium coals have been used as the experimental subjects. The abundance of pyrite in each coal has been measured from the absorption corrected diffractograms, which has been constructed from the experimentally measured diffraction intensities and the mass absorption coefficient of each coal sample. The accuracy (accessed from the figure-of-merit and the net count uncertainty associated with the 1.63 Å pyrite peak) as well as the lower limit of detection for pyrite in these coals is presented. The role of the mass absorption coefficient in the conversion of the measured intensity to the absorption corrected intensity is discussed.

Simultaneous Determination of Layer Thickness, Composition, and Mass Absorption by X-Ray Diffraction

1992 ◽  
Vol 7 (4) ◽  
pp. 194-196 ◽  
Author(s):  
Stefano Battaglia ◽  
Marco Franzini ◽  
Leonardo Leoni
Keyword(s):  
Absorption Coefficient ◽  
Simultaneous Determination ◽  
Mass Absorption Coefficient ◽  
Crystalline Substance ◽  
X Ray Diffraction ◽  
Mass Thickness ◽  
Mass Absorption ◽  
Crystalline Substrate ◽  
Quantitative Results

AbstractThis paper describes a new method for the simultaneous determination of mineral composition, mass thickness and mass absorption coefficient of a thin layer of a crystalline substance deposited on a crystalline substrate.The samples were deposited on membrane disc filters, consisting of mixtures of cellulose acetate and cellulose nitrate. Quantitative results are achieved by measuring the diffraction intensity of the analyte and the attenuation of a reflection of the crystalline material supporting the deposited sample. The mean accuracy of the analysis was found to be: ≈ 3% for mass thickness, ≈ 1% for mass absorption coefficient and ≈ 4% for quantitative mineralogical determination.

scholarly journals Absorption Corrections for X-Ray Fluorescence Analysis of Environmental Samples

1975 ◽  
Vol 19 ◽  
pp. 381-391 ◽  
Author(s):  
F. Bazan ◽  
N. A. Bonner
Keyword(s):  
Absorption Coefficient ◽  
Environmental Samples ◽  
Fluorescence Analysis ◽  
Coherent Scattering ◽  
Absorption Coefficients ◽  
X Ray

The discovery of a very simple and useful relationship between the absorption coefficient of a particular element and the ratio of incoherent to coherent scattering by the sample containing the element is discussed. By measuring the absorption coefficients for a few elements in a few samples, absorption coefficients for many elements in an entire set of similar samples can be obtained.

Absorption Coefficients of Inelastic Dynamic X-Ray Diffraction

2014 ◽  
pp. 483-502
Keyword(s):  
Absorption Coefficient ◽  
Inelastic Scattering ◽  
Waller Factor ◽  
Time Dependent ◽  
X Ray Diffraction ◽  
Absorption Coefficients ◽  
X Ray ◽  
Charge Current ◽  
Dispersion Equations ◽  
Debye Waller Factor

The X-ray inelastic scattering phenomena during the time-dependent perturbations are described with the aid of dynamical dispersion equations coupled with charge current in the Maxwell equations towards the appearance of the Debye-Waller factor driving the absorption coefficient, either for inelastic thermal diffusion and the Compton scattering, respectively.

Mass Absorption Coefficient Measurements Using Thin Films

1969 ◽  
Vol 13 ◽  
pp. 632-638 ◽  
Author(s):  
P. Lublin ◽  
P. Cukor ◽  
R. J. Jaworowski
Keyword(s):  
Thin Films ◽  
Absorption Coefficient ◽  
Mass Absorption Coefficient ◽  
Absorption Coefficients ◽  
Electron Probe Analysis ◽  
Mass Absorption ◽  
Probe Analysis ◽  
Absorption Correction ◽  
Thin Foils ◽  
Metal Organic

For quantitative electron probe analysis, the raw intensity ratios must be corrected to take into account deviations due to absorption, fluoresecnce and electron beam penetration. The major correction is usually the absorption correction, so that for best results, accurate mass absorption coefficients are required. Many tables of absorption coefficients are calculated by interpolation or extrapolation from available measured values, and therefore new measurements are required for increased reliability. The region which requires the most attention for present-day probe analysis is the 2 to 10 Å range.Thin foils of the lighter metals are available for mass absorption coefficient measurements, but heavy metal foils, which must be extremely thin, are not obtainable, A method has been developed to prepare thin films of heavy metals on a suitable substrate by pyrolytic decomposition of metal organic compounds.

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