The three-dimensional point spread function of aberration-corrected scanning transmission electron microscopy

Area of Science:

• Electron microscopy
• Materials science
• Nanotechnology

Background:

• Aberration correction in scanning transmission electron microscopy (STEM) enhances imaging capabilities.
• Three-dimensional (3D) imaging via depth sectioning offers sub-Ångstrom lateral resolution and nanometer depth sensitivity.
• Optimizing depth resolution is crucial for imaging thick biological specimens.

Purpose of the Study:

• To investigate the three-dimensional (3D) probe shape in STEM.
• To understand how aberrations influence probe shape and depth resolution.
• To explore methods for improving 3D imaging of thick samples and nanoparticles.

Main Methods:

• Analysis of probe shape in three dimensions (3D) in STEM.
• Examination of the effects of aberrations on probe shape.
• Theoretical investigation of oversized and annular apertures for vertical resolution enhancement.

Main Results:

• Aberrations significantly alter the 3D probe shape.
• Off-axial aberrations are important for focal series of large areas.
• Oversized or annular apertures theoretically improve vertical resolution for 3D imaging of nanoparticles.
• Optimized regular STEM achieved vertical resolution comparable to aberration-corrected STEM for nanoparticles.

Conclusions:

• Understanding 3D probe shape is key to optimizing depth resolution in STEM.
• Aperture design and aberration control are critical for high-resolution 3D imaging.
• Regular STEM can be optimized for improved vertical resolution in nanoparticle imaging.