High-Speed Three-Dimensional Scanning Force Microscopy Visualization of Subnanoscale Hydration Structures on...

Area of Science:

• Solid-state chemistry
• Surface science
• Geochemistry

Background:

• Hydration at solid-liquid interfaces is crucial in biology, materials science, and Earth science.
• Atomic-scale dynamics of hydration are difficult to visualize directly.
• Conventional measurement methods lack the resolution and speed to capture these dynamics.

Purpose of the Study:

• To develop a high-speed, 3D scanning force microscopy technique for visualizing solid-liquid interfaces.
• To capture the atomic-scale dynamics of hydration at these interfaces.
• To investigate the intermediate states during calcite dissolution in water.

Main Methods:

• Developed a high-speed 3D scanning force microscopy technique.
• Achieved subnanoscale resolution at a rate of 1.6 seconds per 3D image.
• Applied the technique to study calcite dissolution in water.

Main Results:

• Acquired direct 3D images of moving step edges during calcite dissolution.
• Visualized hydration structures in transition regions at the solid-liquid interface.
• Identified a calcium hydroxide (Ca(OH)2) monolayer as an intermediate state.
• Observed hydration layers stabilizing adsorbed Ca(OH)2.

Conclusions:

• The new technique enables unprecedented visualization of hydration dynamics at solid-liquid interfaces.
• Revealed the formation of a Ca(OH)2 monolayer during calcite dissolution.
• Demonstrated the role of hydration layers in stabilizing intermediates.
• Provides insights unobtainable with conventional 1D/2D methods.