Characterization of atmospheric particles by electron probe X-ray microanalysis

Area of Science:

• Materials Science
• Analytical Chemistry
• Geochemistry

Background:

• Accurate elemental quantification of microparticles is crucial for various scientific disciplines.
• Traditional methods often require extensive calibration and may be sensitive to particle size.
• Electron probe X-ray microanalysis (EPMA) offers high spatial resolution for elemental analysis.

Purpose of the Study:

• To validate a novel, standardless quantitation method for microchemical analysis using EPMA.
• To assess the method's applicability to individual particles across different X-ray emission lines.
• To evaluate the method's performance concerning particle size and elemental composition.

Main Methods:

• Utilized microchemical glass standards for method validation.
• Employed a quantitation algorithm based on peak-to-background (P/B) ratios from EPMA spectra.
• Applied the standardless method to determine elemental concentrations in glass particles (1-20 microm) using Malpha, Lalpha, and Kalpha lines.

Main Results:

• The standardless P/B ratio method demonstrated accurate elemental quantification, independent of particle size.
• Concentration results closely matched certified values for most elements, with a noted exception for Sodium (Na) due to potential migration under electron bombardment.
• The method successfully classified qualitative EPMA data for aerosol particles.

Conclusions:

• The developed standardless P/B ratio method provides a robust and size-independent approach for elemental analysis of microparticles via EPMA.
• This technique enhances the efficiency and accuracy of microparticle characterization, particularly for aerosol research.
• Further investigation into mitigating Sodium migration effects is recommended for comprehensive elemental analysis.