atomicforce

Atomic force refers to the forces acting between atoms that determine the properties of matter at the nanoscale. These forces include short-range Pauli repulsion when electron clouds overlap, longer-range attractive van der Waals interactions, and electrostatic forces in charged systems. Understanding atomic forces is essential for predicting adhesion, friction, and mechanical behavior of surfaces.

Atomic force microscopy uses a sharp tip attached to a flexible cantilever to probe these forces. The tip scans a sample; a laser reflects off the cantilever into a photodetector, converting bending into a force measurement. By calibrating the cantilever’s spring constant, the instrument translates deflections into force, enabling maps of surface structure with nanometer resolution.

Measurement modes include contact mode (continuous tip-sample contact), tapping or intermittent-contact mode (oscillating tip that lightly contacts the surface), and non-contact mode (detecting long-range attractions while keeping the tip near but not touching). Each mode trades resolution for reduced sample damage and different force regimes.

Applications span materials science, chemistry, and biology, including imaging hard and soft surfaces, measuring local stiffness, adhesion, and friction, and performing force-distance spectroscopy to quantify interaction forces. Variants such as Kelvin probe force microscopy, magnetic force microscopy, and electrostatic force microscopy extend AFM to electrical, magnetic, and work-function mapping.