Three-Dimensional Electron Microscopy of Chiral Nanoparticles: From Imaging to Measuring

Area of Science:

• Nanotechnology and Materials Science
• Surface Science and Characterization
• Optical Physics and Plasmonics

Background:

• Growing interest in intrinsically chiral plasmonic nanoparticles necessitates advanced characterization beyond qualitative imaging.
• Chiral nanoparticles exhibit reduced symmetry and strong optical activity, making their precise structural determination critical.
• Traditional imaging methods are insufficient for fully understanding the complex 3D structures of these nanoparticles.

Purpose of the Study:

• To review recent advances in three-dimensional electron microscopy (3D EM) techniques for characterizing chiral metallic nanoparticles.
• To highlight how 3D EM data analysis, including geometric chirality quantification, informs structure-property relationships and simulations.
• To present new insights into nanoparticle growth pathways enabled by 3D characterization and to offer future outlooks.

Main Methods:

• Focus on scanning electron microscopy (SEM), electron tomography, and secondary electron electron-beam-induced current (SEEBIC) as key 3D EM techniques.
• Discussion of data analysis strategies for retrieving explicit 3D shapes and quantitative geometric information.
• Integration of 3D structural data with electromagnetic simulations to understand optical properties.

Main Results:

• 3D EM techniques provide detailed surface information and enable the retrieval of explicit 3D shapes of chiral nanoparticles.
• Quantitative analysis of geometric chirality from 3D EM data correlates with nanoparticle optical activity.
• 3D characterization reveals previously unobserved nanoparticle growth pathways and mechanisms.

Conclusions:

• 3D EM is a powerful tool for the detailed structural and morphological characterization of chiral plasmonic nanoparticles.
• Quantitative 3D structural data is essential for understanding the relationship between nanoparticle shape and optical properties.
• Future applications of 3D EM will further advance the design and development of novel chiral nanomaterials.