February 18, 2008
What Type Of Microscope Is Used To View Atoms?
The atomic force microscope (AFM) is used to view atoms. This microscope is a very high resolution microscope that has resolutions of the fractions of a nanometer. The term ‘microscope’ for this instrument is actually misleading because a microscope studies specimens by ‘seeing’ them but an AFM studies them by ‘feeling’ the specimens with a mechanical probe. This probe is made possible by piezoelectric elements that enable exact and specific movements on electronic command.
An earlier version of the AFM, the scanning tunneling microscope or the STM, was developed by Heinrich Rohrer and Gerd Binnig, two German scientists, who received the Nobel Prize for this invention in 1986. This year was a momentous one for microscopes that could view atoms. The AFM was invented by Binnig, Gerber and Quate in 1986.
Some Useful Pointers
A scanning probe microscope does not use lenses.
The AFM works by measuring attractive or repulsive forces between a tip and the sample (Bennig).
It can accomplish resolutions of 10 pm.
The AFM is different from an electron microscope because it can view specimens in air and under liquids.
The AHM basically works on the same principal as a record player but with a few modifications. These are - Force feed back, sharp tips, sensitive detection, high resolution tip sample positioning and cantilevers.
The Advantages Of An AHM Over A Scanning Electron Microscope
The dimension advantage-The SEM provides only a 2 dimensional image, but an AHM provides an actual 3 dimensional image.
No metal coatings required for viewing- Specimens or samples used under an AHM do not require undergoing any exceptional treatments.
The environment advantage- The AHM can function properly in air and liquid environments unlike a SEM which requires a high vacuum environment. Therefore biological macromolecules and living micro-organisms can also be observed under it.
The resolution advantage- The AFM provides a much higher resolution than the SEM, and it can cause atomic resolution in Ultra High Vacuum.
The Disadvantages Of An AHM Over An SEM
Disadvantage of image size- While an SEM can measure area and depth of millimeters, an AHM can only measure the height and scanning area of micrometers.
Disadvantage of image distortion- The image can get distorted if the wrong tip is used for a required resolution.
Disadvantage of speed- The AHM cannot scan images as fast an SEM.
That was an account on the Atomic Force Microscope. I hope you enjoyed reading it. For further information, you can read some superior science magazines and surf the net as well.
