Reducing electron beam damage through alternative STEM scanning strategies, Part I: Experimental findings

Area of Science:

• Materials Science
• Microscopy
• Chemistry

Background:

• High-energy electrons in transmission electron microscopes (TEM) can damage sensitive samples, hindering analysis.
• This beam damage is a significant challenge for materials like zeolites, organic, and biological samples.
• Previous studies on beam damage suffered from reproducibility issues and a lack of robust data.

Purpose of the Study:

• To experimentally investigate the influence of scanning probe patterns on electron beam damage in zeolites.
• To establish reproducible experimental conditions for studying beam damage.
• To compare beam damage resulting from conventional raster scans versus a novel interleaved scan pattern.

Main Methods:

• Utilized a programmable scan engine for precise control over electron probe distribution.
• Conducted repeated experiments under identical conditions comparing raster and interleaved scan patterns.
• Quantified beam damage by measuring mass loss in zeolite samples.

Main Results:

• Observed a significant difference in beam damage between the two scan patterns.
• The interleaved scan pattern resulted in up to an 11% reduction in mass loss compared to the raster scan.
• Demonstrated that scan pattern is a critical, previously underappreciated factor in electron beam damage.

Conclusions:

• Electron beam damage in scanning transmission electron microscopy (STEM) is not solely dependent on electron dose, dose rate, or acceleration voltage.
• The spatial distribution of the electron probe, controlled by the scan pattern, significantly impacts beam damage.
• Future STEM experiments should consider scan pattern optimization to minimize sample damage and improve data quality.