Atomic Force Microscopy (AFM) with the Bruker Dimension Icon PT
A Dimension Icon PT from Bruker (formerly Veeco) is used in the Coatings, Materials & Polymers department at Paderborn University's Department of Chemistry.
Atomic force microscopes (AFM) are also known as Rasterkraftmikroskope (RKM) or Atommikroskope. In English-speaking countries, the terms atomic force microscope (AFM) and scanning force microscope (SFM) are commonly used. They are used to observe surfaces on a micro or nano scale. Using a very fine needle (tip), the surface of the sample to be examined is scanned line by line. Point by point, line by line, an image of the surface topography is created. In addition to the topography image, newer and newer measuring methods make it possible to resolve more and more material properties (magnetism, magnetizability, friction, elasticity, hardness, etc.) and now even their chemical composition. Depending on the device and measuring conditions, resolutions down to the atomic scale can be achieved.
Measuring principle and design
A very finely pointed measuring tip is attached to a leaf spring (cantilever). Typical diameters of the measuring tip are 30 nm to less than 1 nm (atomic scale). Interactions with the sample surface lead to the applied force, which can bend the cantilever according to Hooke's law:
Force = - Force constant ⋅ Deflection
The deflection of the spring is measured indirectly using a laser whose reflected light falls into a four-quadrant photodetector. In addition to the deflection of the cantilever, it can also be moved in the z-direction using a piezo element. Depending on the device, the movements in the x and y directions are realized by moving the measuring probe or the sample stage.