Enhancing atomic force microscopy stability through second harmonic optical fibre cavity control

Area of Science:

• Materials Science
• Surface Physics
• Nanotechnology

Background:

• Interatomic potentials govern material properties.
• Conventional atomic force microscopy (AFM) struggles to directly measure tip-sample interactions due to limited distance control.
• Existing methods often measure deflection versus displacement, not direct force-distance relationships.

Purpose of the Study:

• To propose and demonstrate a novel methodology for directly measuring tip-surface interactions as a function of tip-sample distance.
• To overcome the limitations of conventional AFM in quantifying interatomic potentials.
• To provide a more accurate approach for characterizing forces at the nanoscale.

Main Methods:

• Utilizing an AC interferometer to precisely monitor absolute tip displacement.
• Implementing a negative feedback loop to maintain constant tip position by adjusting the cantilever anchoring point.
• Actively controlling the tip-sample distance to a point of maximum interferometer sensitivity.

Main Results:

• Direct measurement of tip-surface interactions as a function of tip-sample distance.
• Successful prevention of tip-jump-to-contact phenomena, ensuring stable measurements.
• Accurate determination of indentation depth through sample motion tracking.

Conclusions:

• The proposed methodology offers a direct and accurate way to measure interatomic potentials.
• This technique enhances the capabilities of force microscopy by providing precise distance control.
• The findings pave the way for improved characterization of material properties at the atomic scale.