Automating ALCHEMI at the nano-scale using software compatible with PC-controlled transmission electron microscopy.

Area of Science:

• Materials Science
• Analytical Chemistry
• Electron Microscopy

Background:

• Atom location by channeling-enhanced microanalysis (ALCHEMI) provides atom-site-specific elemental information in crystalline samples.
• High-angular-resolution electron-channeled X-ray/electron spectroscopy (HARECXS/HARECES) is a quantitative extension of ALCHEMI.
• Current automated methods are limited to analyzing regions of 1 µm or larger.

Purpose of the Study:

• To overcome the minimum analysis area limitation of current ALCHEMI techniques.
• To enable ALCHEMI and its derivative methods on nanoscale regions without hardware modification.
• To develop a more sophisticated and automated scheme for high-resolution elemental analysis.

Main Methods:

• Modification of the quantitative electron diffraction (QED) software plug-in within the Gatan Microscopy Suite.
• Development of a new scheme for QED to perform ALCHEMI using energy-dispersive X-ray spectroscopy (EDX) and/or electron energy-loss spectroscopy (EELS).
• Calibration and control of the electron probe for precise positioning during beam tilting.

Main Results:

• The modified QED enables automated ALCHEMI on areas as small as 30 nm.
• The new scheme allows for concurrent EDX and EELS analysis.
• The method is compatible with any PC-controlled commercial microscope without hardware changes.

Conclusions:

• The developed QED-based ALCHEMI method significantly reduces the minimum analysis area.
• This technique provides unprecedented nanoscale elemental site-specific analysis capabilities.
• The approach democratizes advanced analytical techniques for smaller sample areas.