Quantifying signal quality in scanning transmission X-ray microscopy.
Benjamin Watts1, Simone Finizio1, Jörg Raabe1
1Swiss Light Source, Paul Scherrer Institute, Forschungsstrasse 111, 5232 Villigen, Switzerland.
Journal of Synchrotron Radiation
|July 5, 2022
Summary
Optimizing scanning transmission X-ray microscopy (STXM) data quality requires understanding experimental factors. This study details signal uncertainties and distortions, recommending sample optical densities around 1 for improved STXM measurements.
Area of Science:
- Materials Science
- Spectroscopy
- Microscopy
Background:
- General understanding of photon flux and sample thickness effects on scanning transmission X-ray microscopy (STXM) data quality is limited.
- Misconceptions regarding STXM experimental design and execution can arise from a lack of detailed information.
- Formal treatment of transmission signal uncertainties and distortions in STXM is needed to improve data quality.
Purpose of the Study:
- To provide a formal treatment of uncertainty and distortions in STXM transmission signals.
- To establish a rational basis for maximizing data quality in STXM experiments.
- To present a method for assessing higher-order suppression's impact on STXM transmission measurements.
Main Methods:
- Formal analysis of transmission signal uncertainty sources: dark counts, higher-order photons, and resolution limitations.
- Investigation of the impact of sample thickness and optical density on data quality.
- Development of a quantitative method to evaluate the benefits of higher-order light suppression.
Main Results:
- An optimal sample optical density of 2.2 is identified under ideal STXM conditions.
- Distortion effects are more pronounced in thicker samples, suggesting an optical density of ~1 is recommended.
- A method for objectively assessing higher-order suppression in STXM beamline design is presented.
Conclusions:
- Understanding and mitigating signal uncertainties and distortions are crucial for high-quality STXM data.
- Sample thickness and optical density significantly influence data fidelity, with thinner samples preferred when distortions are present.
- The developed assessment method aids in optimizing synchrotron beamline design for improved STXM performance.
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