Dynamic Imaging of Nanostructures in an Electrolyte with a Scanning Electron Microscope

Area of Science:

• Electron Microscopy
• Nanotechnology
• Electrochemistry

Background:

• Microfabricated liquid cells enable dynamic electron microscopy of nanostructures in liquid environments.
• Implementing liquid cells in scanning electron microscopes (SEM) allows for multi-modal studies due to larger chamber volumes and detector integration.

Purpose of the Study:

• To describe an electrochemical liquid cell SEM platform.
• To demonstrate imaging of copper oxide nanoparticles in solution using backscattered and transmitted electrons.
• To analyze contrast inversion in transmitted electron images for liquid layer thickness determination.

Main Methods:

• Utilized microfabricated liquid cells with silicon nitride membranes, similar to those in transmission electron microscope (TEM) holders.
• Employed an electrochemical setup within the SEM.
• Performed imaging using both backscattered electrons and transmitted electrons.
• Conducted Monte Carlo simulations to analyze imaging modes and contrast mechanisms.

Main Results:

• Successfully imaged copper oxide nanoparticles in solution using the liquid cell SEM.
• Observed contrast inversion in transmitted electron images at specific liquid layer thicknesses (hundreds of nanometers).
• Demonstrated the capability to image tens-of-nanometer sized nanoparticles.
• Monte Carlo simulations supported the advantages of different imaging modes for liquid phase studies and explained the observed contrast inversion.

Conclusions:

• The developed electrochemical liquid cell SEM platform is effective for in-situ nanoscale imaging in liquids.
• Transmitted electron imaging provides a method for detecting liquid presence and thickness.
• Both backscattered and transmitted electron imaging modes offer complementary information for liquid phase electron microscopy.