Complex force dynamics in atomic force microscopy resolved by wavelet transforms

Area of Science:

• Physics
• Materials Science
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) relies on tip-sample interactions.
• Understanding these interactions at the nanoscale is crucial for material characterization.
• Cantilever dynamics play a key role in AFM measurements.

Purpose of the Study:

• To investigate the amplitude and phase evolution of cantilever oscillations post-impact.
• To reconstruct the instantaneous total force during a single tip-sample interaction.
• To enhance the capabilities of atomic force spectroscopy for single interactions.

Main Methods:

• Cross-correlation wavelet analysis was employed.
• Simultaneous extraction of instantaneous amplitude and phase at all frequencies.
• Analysis focused on the dynamics following a single tip-sample impact.

Main Results:

• Evidence of multiple flexural mode excitation was observed.
• Instantaneous amplitude and phase evolution were successfully extracted.
• The total instantaneous force acting on the tip was reconstructed.

Conclusions:

• The developed method allows detailed analysis of tip-sample interactions.
• This technique is relevant for atomic force spectroscopy of single interactions.
• Understanding cantilever eigenmodes and harmonics is key for precise force reconstruction.