A practical method for performing full-tilt-angle electron tomography of submicron-sized particles.

Area of Science:

• Materials Science
• Nanotechnology
• Microscopy

Background:

• Transmission electron microscopy (TEM) is crucial for nanoscale imaging.
• Full-tilt-angle tomography is challenging for submicron particles due to limitations in specimen holders and potential sample damage.
• Existing methods often suffer from the missing wedge effect, limiting 3D reconstruction accuracy.

Purpose of the Study:

• To develop a practical method for full-tilt-angle electron tomography of nanometer-sized particles.
• To overcome limitations of existing tomography techniques, including sample damage and the missing wedge effect.
• To enable rapid and accurate 3D reconstruction of submicron particle morphology.

Main Methods:

• Designed a specialized specimen holder for a 200-kV TEM compatible with a ±90° tilt range.
• Developed a protocol using focused ion beam (FIB) and scanning electron microscopy (SEM) to attach particles to a tungsten needle via carbon deposition, minimizing Ga ion beam damage.
• Integrated the tungsten needle with the specimen holder for seamless tilting within the TEM.
• Acquired tilt series images of polystyrene latex and ZnO tetrapod particles.

Main Results:

• Achieved clear 3D reconstructions of submicron particle shapes without the missing wedge effect.
• Demonstrated fast tomography of ZnO particles using a 25-s movie, yielding results comparable to conventional methods requiring over an hour.
• Verified the mechanical stability of attached particles through atomic-resolution imaging of TiSe2 flakes.

Conclusions:

• The developed method provides a practical and efficient approach for full-tilt-angle electron tomography of nanometer-sized particles.
• This technique significantly reduces acquisition time and improves the accuracy of 3D reconstructions.
• The protocol minimizes sample damage, ensuring high-quality TEM observations and reliable structural analysis.