Atomic force microscopy (AFM) is a high-resolution imaging technique that is used to obtain surface topography information on the nanometer scale. It works by scanning a sharp tip across the surface of a sample, while measuring the deflection of a cantilever that is in contact with the surface.
The basic components of an AFM system include a sample stage, a piezoelectric scanner, a cantilever, a laser beam, and a photodetector. The sample is mounted on the sample stage, which can move in three dimensions using the piezoelectric scanner. The cantilever, which is typically made of silicon or silicon nitride, is attached to the scanner and has a sharp tip at the end.
As the scanner moves the cantilever across the surface of the sample, the tip interacts with the surface and causes the cantilever to deflect. The deflection of the cantilever is measured using a laser beam that is focused on the back of the cantilever and detected by a photodetector. The position of the scanner is adjusted in real-time based on the deflection of the cantilever, in order to maintain a constant force between the tip and the surface.
The output of an AFM system is typically a topographic image of the surface, which shows the height variations of the sample with nanometer resolution. In addition to topography, AFM can also be used to measure other physical properties of the sample, such as friction, adhesion, and elasticity.
AFM has a wide range of applications in materials science, biology, and nanotechnology. It can be used to study the surface morphology of a variety of samples, including biological molecules, polymers, and semiconductors. AFM can also be used to manipulate and characterize individual atoms and molecules, making it a powerful tool for nanotechnology research.
One of the main advantages of AFM is its ability to operate in a variety of environments, including air, vacuum, and liquid. This makes it a useful tool for studying biological systems, which often require a liquid environment. Additionally, AFM is non-destructive and can be used to study samples without damaging or altering them.