Measures for spectral quality in low-voltage X-ray microanalysis.

Area of Science:

• Materials Science
• Physics
• Analytical Chemistry

Background:

• Characteristic x-ray production is sensitive to overvoltage, the ratio of beam energy to excitation energy.
• Low-voltage electron microscopy (beam energy ≤ 5 keV) is prone to sample charging, affecting x-ray peak intensities.
• Sample charging can introduce significant artifacts in microanalysis.

Purpose of the Study:

• To investigate the impact of sample charging on low-voltage x-ray microanalysis.
• To identify methods for detecting and mitigating charging artifacts in electron microscopy.
• To ensure accurate elemental analysis in challenging low-voltage conditions.

Main Methods:

• Analysis of overvoltage effects on characteristic x-ray production.
• Utilizing the Duane-Hunt bremsstrahlung limit as a diagnostic for sample charging.
• Employing time series experiments and dynamic energy windows to monitor dynamic charging effects.
• Evaluating the efficacy of conductive surface coatings and conductive grids.

Main Results:

• Low overvoltage in low-energy electron beams exacerbates sample charging issues.
• The Duane-Hunt limit can indicate static charging, but dynamic effects require further investigation.
• Time series analysis and dynamic energy windows are effective for observing dynamic charging.
• Conductive coatings and grids successfully mitigate charging artifacts, enabling data acquisition.

Conclusions:

• Sample charging is a critical artifact in low-voltage x-ray microanalysis that can distort results.
• The Duane-Hunt limit is a useful, but not exhaustive, indicator of charging.
• Dynamic charging effects necessitate specific monitoring techniques.
• Surface coatings or conductive grids are practical solutions for obtaining reliable x-ray spectra from charging samples.