Design and use of a flow cell for observing evolving solid-fluid interfaces in a scanning electron microscope.

Area of Science:

• Materials Science
• Analytical Chemistry
• Surface Science

Background:

• Observing dynamic solid-fluid interactions in situ is crucial for understanding material degradation and formation processes.
• Existing methods often lack the capability to maintain stable chemical environments or provide direct visualization of complex surface phenomena.
• Scanning Electron Microscopy (SEM) offers high-resolution imaging but typically requires a vacuum, limiting in-situ fluid studies.

Purpose of the Study:

• To develop and characterize a novel fluid flow cell for direct in-situ observation of fluid-solid interactions within a scanning electron microscope.
• To enable the study of complex processes such as corrosion, dissolution, and nucleation/growth directly on solid surfaces.
• To ensure stable chemical conditions during experiments through continuous fluid circulation.

Main Methods:

• Development of a specialized fluid flow cell with an electron-transparent silicon nitride (SiNx) window to interface fluid and vacuum environments.
• Utilizing backscattered electron (BSE) imaging mode in the SEM for surface observation.
• Employing Monte Carlo (MC) simulations to model electron trajectories and backscattered electron emissions for contrast interpretation and operational limit determination.

Main Results:

• The developed fluid flow cell allows for direct visualization of dynamic processes occurring at solid material surfaces during fluid exposure.
• Continuous fluid circulation effectively maintains constant chemical conditions, crucial for reproducible experiments.
• Observed BSE contrasts correlate well with MC simulations, validating the imaging approach and the cell's performance.

Conclusions:

• The novel fluid flow cell is a significant advancement for in-situ studies of solid-fluid interactions in SEM.
• It provides a robust platform for investigating complex surface phenomena like corrosion and material growth under controlled chemical environments.
• The integration with BSE imaging and MC simulations enhances the interpretation and reliability of experimental results.