Improvements in fundamental performance of in-liquid frequency modulation atomic force microscopy

Area of Science:

• Surface science
• Nanotechnology
• Physical chemistry

Background:

• In-liquid frequency modulation atomic force microscopy (FM-AFM) visualizes subnanometer surface structures.
• Three-dimensional atomic force microscopy (3D-AFM) visualizes hydration and molecular chains.
• Previous FM-AFM had limitations in force resolution, speed, and stability.

Purpose of the Study:

• To detail recent improvements in FM-AFM's fundamental performances.
• To highlight new possibilities for studying solid-liquid interfaces at the atomic scale.

Main Methods:

• Utilizing smaller cantilevers to dramatically improve force resolution.
• Enhancing imaging speed by improving bandwidth, resonance frequency, and latency, including high-speed phase-locked loop (PLL) circuits.
• Applying a silicon (Si)-coating method to the tip apex for improved stability and reproducibility.

Main Results:

• Achieved 3D hydration structure imaging even in pure water.
• Enabled atomic-resolution in-liquid FM-AFM imaging at approximately 1 second per frame.
• Demonstrated improved stability and reproducibility of atomic-resolution imaging.

Conclusions:

• Recent advancements have overcome previous limitations in FM-AFM.
• Atomic-scale studies of solid-liquid interfacial phenomena are now more feasible.
• Improved FM-AFM offers new avenues for research in materials science and nanotechnology.