Difference Between AFM and SEM
Smaller world exploration has been quickly growing with the development of new technologies like nanotechnology, microbiology and electronics. Since microscope is the tool which provides the magnified images of the smaller objects, a lot of research is done on developing different techniques of microscopy to increase the resolution. In the first microscope, an optical solution was used where lenses magnified the images. However, themodern high resolution microscopes follow dissimilar approaches. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) are based on two of such diverse approaches.
Atomic Force Microscope (AFM)
AFM uses a tip to scan the surface of the sample and tip goes up and down according to the nature of the surface. This impression is similar to the way in which a blind person understanding a surface by running his fingers all over the surface. Gerd Binnig and Christoph Gerber in 1986 introduced the AFM technology. It was commercially accessible since 1989.
The slant isattached to a cantilever and made of materials such ascarbon nanotubes, diamond and silicon. Smaller tip higher the resolution of the imaging. The majority of the present AFMs have a nanometer resolution. Dissimilar types of methods are used to measure the displacement of the cantilever. Laser beam is themost common method which reflects on cantilever so that the deflected beam’s reflection beam can be used as a gauge of the cantilever position.
The method of producing a 3D image of the sample by inquiring the surfaces is proficient since a mechanical probe is used to feel the surface by AFM. It is also enables users to manipulate the atoms or molecules on the sample surface using the tip.
Scanning Electron Microscope (SEM)
SEM uses an electron beam instead of light for imaging. It has a large profundity in field which enables users to observe a more detailed image of the sample surface. AFM also has a more control in amount of magnification as an electromagnetic system is in use.
In SEM, the beam of electrons is produced using an electron gun and it goes through a vertical path along the microscope which is placed in a vacuum. Electrical and magnetic fields with lenses center the electron beam to the specimen. Once the electron beam hits on the sample surface, electrons and X-rays are emitted. These emissions are detected and analyzed in order to put the material picture on the screen. Resolution of SEM is in nanometer scale and it depends on the beam energy.
While SEM is operated in a vacuum and also uses electrons in the imaging process, special events should be followed in sample preparation.
SEM has a very long narration since its first observation done by Max Knoll in 1935. Primary commercial SEM was available in 1965.