What is an atomic force microscope (AFM)?
Q: What is an atomic force microscope (AFM)?
A: An atomic force microscope (AFM) is a type of microscope that provides pictures of atoms on or in surfaces. It can be used to look at individual atoms and is commonly used in nanotechnology.
Q: How does the AFM work?
A: The AFM works by employing an ultra-fine needle attached to a cantilever beam. The tip of the needle runs over the ridges and valleys in the material being imaged, "feeling" the surface. As the tip moves up and down due to the surface, the cantilever deflects. In one basic configuration, a laser shines on the cantilever at an oblique angle, allowing for direct measurement of deflection in the cantilever by changing its angle of incidence for the laser beam. This creates an image revealing configuration of molecules being imaged by machine.
Q: What are some advantages that AFMs have over scanning electron microscopes (SEMs)?
A: AFMs provide higher resolution than SEMs and do not need to operate in a vacuum like SEMs do - they can operate in ambient air or water, allowing them to be used with biological samples such as living cells without damaging them.
Q: What are some operating modes for AFMs?
A: Commonly used operating modes for AFMs include contact mode, where tip is simply moved across surface and cantilever deflections are measured; tapping mode, where tip is tapped against surface as it travels along; intermittent contact mode; non-contact mode; dynamic mode; static mode; and more - these are often variations on tapping and contact modes described above.
Q: How does tapping mode differ from contact mode?
A: Tapping mode differs from contact mode because when using tapping mode, tip taps against surface as it travels along instead of just moving across it - this allows it to move away from surface when needle feels ridge so that it will not hit against surface when moving across which makes it useful for soft surfaces such as biological samples since less likely to damage them this way.
