Compositional averaging of continuum intensities in multielement compounds

Area of Science:

• Materials Science
• Analytical Chemistry
• Physics

Background:

• Accurate prediction of X-ray continuum production in compounds is crucial for quantitative analysis.
• Traditional methods rely on mass-fraction weighted averaging, which may not accurately reflect underlying physical processes.

Purpose of the Study:

• To investigate the physical basis of X-ray continuum production in compounds.
• To compare the efficacy of mass-fraction versus electron-fraction weighted averaging for predicting compound continuum.
• To determine the influence of isotopic mass on continuum production.

Main Methods:

• Electron probe microanalysis (EPMA) was used to measure X-ray continuum.
• Experiments involved pure elements, compounds, and pairs of stable isotopes.
• Continuum production was analyzed using both mass-fraction and electron-fraction weighted averaging models.

Main Results:

• No physical basis was found for mass-fraction weighted averaging of X-ray continuum in compounds.
• Measurements using stable isotopes confirmed that mass (neutron number) does not affect continuum production.
• Electron-fraction weighted averaging demonstrated superior accuracy in predicting compound continuum from elemental measurements.

Conclusions:

• Mass-fraction averaging is an inadequate method for estimating X-ray continuum production in compounds.
• Electron-fraction averaging provides a more physically grounded and accurate approach.
• Understanding elemental contributions to electron composition is key for accurate quantitative analysis in EPMA.