Quantitative EDXS: Influence of geometry on a four detector system

Area of Science:

• Materials Science
• Analytical Chemistry
• Microscopy

Background:

• Quantitative energy dispersive X-ray spectrometry (EDXS) is crucial for elemental analysis in materials science.
• The geometry of detector placement and specimen holder design can introduce significant errors in EDXS quantification.
• Accurate elemental quantification requires understanding and correcting for geometric effects like detector shadowing and X-ray absorption.

Purpose of the Study:

• To investigate the influence of system geometry on quantitative EDXS analysis using a Super-X detector system.
• To determine the precise positions of Super-X detectors through combined experimental and simulation methods.
• To assess the impact of specimen holder geometry and detector shadowing on the quantification of elements, particularly low to medium atomic number ones.

Main Methods:

• Utilized a ChemiSTEM system with a Super-X detector configuration and a low-background double-tilt specimen holder.
• Combined experimental measurements with Monte Carlo simulations to precisely determine detector positions.
• Calculated detector solid angles, estimated shadowing effects, and applied the ζ-factor method for absorption correction.

Main Results:

• Established accurate detector positions for the Super-X system, enabling precise solid angle calculations.
• Quantified the significant influence of detector shadowing, caused by the specimen holder (brass and beryllium components), on EDXS analysis.
• Demonstrated that shadowing severely affects the quantification of low to medium atomic number elements.

Conclusions:

• Detector shadowing and specimen holder geometry are critical factors that must be addressed for accurate EDXS quantification.
• The study provides a methodology for correcting geometric effects in multi-detector EDXS systems.
• Implementing corrections and optimizing holder design can minimize systematic errors and improve the reliability of quantitative EDXS analysis.