Dissipation signals due to lateral tip oscillations in FM-AFM

Area of Science:

• Physics
• Materials Science
• Surface Science

Background:

• Frequency-modulated dynamic atomic force microscopy (FM-DAFM) relies on tip-surface interactions for imaging.
• Coupling between normal and lateral tip oscillations is influenced by tip-surface forces.

Purpose of the Study:

• To investigate the coupling between lateral and normal tip oscillations in FM-DAFM.
• To understand how this coupling affects the atomic-scale imaging process.
• To explore the resulting contrast mechanisms for ionic crystals.

Main Methods:

• Theoretical analysis of coupled tip oscillations.
• Modeling energy transfer between normal and lateral excitations.
• Simulating imaging of ionic crystal surfaces.

Main Results:

• Tip-surface interaction induces coupling between normal and lateral tip oscillations.
• Energy transfer from normal to lateral oscillation is observed as damping.
• Re-transfer of energy back to normal oscillation can occur, influencing imaging.
• A specific dissipation mechanism leads to atomic contrast with two maxima per unit cell for ionic crystals.

Conclusions:

• The coupling of tip oscillations is a significant factor in FM-DAFM imaging.
• This coupling mechanism can generate high-resolution atomic contrast.
• Understanding this phenomenon enhances the capabilities of atomic force microscopy for surface analysis.