Introduction

What is an atomic force microscope?

An atomic force microscope, or AFM, uses in its most basic configuration an optical beam deflection system to convert into height data the deflection of a sharp probe scanning the sample (in continuous or intermittent contact). This data can be later used to create a 3D reconstructed sample profile.

The probe, a cantilever beam with a sharp pyramid at one end, touches the sample and moves up and down in sync with the topography of the sample. Depending on the scanning mode, several data channels can be extracted: amplitude, height, and phase shift. Data in-line and post-processing can expand the range of channels to stiffness, Young’s modulus, adhesion, loss-tangent, surface potential, indentation, electrical conductivity.

Given the very low noise floor (several tens of picometres) and precise XY piezo crystals’ motion, one can scan, large areas, such as 100×100 µm², or very small domains, 5×5 nm². Such versatility allows detecting atomic lattices and Moiré patterns in air and in fluids.   Z resolution reaches tens of pm and typical systems can handle samples with peak-to-valley dimensions up to 12 µm.

Throughout this module you will learn more about the fundamentals of AFM, and how these capabilities are applied in scientific research.

Next - Applications of AFM

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