Near-field deformation of a liquid interface by atomic force microscopy

Area of Science:

• Nanophysics
• Surface Science
• Fluid Dynamics

Background:

• Understanding liquid-solid interactions is crucial for nanotechnology.
• Atomic Force Microscopy (AFM) is a key tool for nanoscale measurements.
• Previous theoretical models exist for liquid-probe interactions.

Purpose of the Study:

• To experimentally investigate the interaction between liquid puddles and spherical probes.
• To determine the critical distance for liquid wetting of a probe.
• To validate theoretical models of nanoscale liquid-probe interactions.

Main Methods:

• Utilized a novel experimental setup combining AFM, a high-speed camera, and an inverted optical microscope.
• Measured force-distance and frequency shift-distance curves in contact and frequency modulation modes.
• Employed various bulk model liquids with known probe-liquid Hamaker constants.

Main Results:

• Determined the "jump-to-contact" critical distance (d_min) for liquid wetting.
• Demonstrated that probe-liquid interaction at the nanoscale is governed by liquid interface deformation.
• Observed excellent agreement between experimental data and theoretical models.

Conclusions:

• The study validates theoretical predictions of nanoscale liquid-probe interactions.
• Liquid interface deformation is the primary factor controlling wetting at the nanoscale.
• This work enables further experimental investigations of nanoscale liquid behavior.