A high-pressure atomic force microscope for imaging in supercritical carbon dioxide.

Area of Science:

• Materials Science
• Geochemistry
• Physical Chemistry

Background:

• Studying solid-fluid interfaces under pressure is crucial for understanding geological and industrial processes.
• Existing atomic force microscopy (AFM) techniques have limitations in handling high-pressure supercritical fluids.

Purpose of the Study:

• To develop and demonstrate a high-pressure atomic force microscope for in situ measurements.
• To enable atomic-scale imaging of solid surfaces in contact with supercritical carbon dioxide (scCO2).

Main Methods:

• Developed a novel high-pressure AFM apparatus capable of operating up to 100 atm and ~350 K.
• Utilized a standard optically-based cantilever deflection detection system.
• Focused on precise pressure and temperature control to minimize fluid density fluctuations.

Main Results:

• Successfully achieved in situ atomic-scale imaging of a calcite (CaCO3) mineral surface in scCO2.
• Visualized single, monatomic steps and dynamic processes on the calcite (1014) surface.
• Demonstrated the capability to overcome previous pressure limitations in hydrothermal AFM.

Conclusions:

• The developed high-pressure AFM provides unprecedented in situ access to interfacial phenomena.
• This technology opens new avenues for studying solid-fluid interactions under challenging pressure conditions.
• Enables detailed investigation of mineral dissolution, precipitation, and surface reactions in scCO2 environments.