Question

In: Chemistry

Compare and contrast scanning tunneling microscopy (STM) and atomic force microscopy (AFM)? List at least two...

Compare and contrast scanning tunneling microscopy (STM) and atomic force microscopy (AFM)? List at least two advantages and two disadvantages for both methods. Please reference at least one source in your discussion

Solutions

Expert Solution

Difference Between AFM and STM

AFM vs STM

AFM refers to Atomic Force Microscope and STM refers to Scanning Tunneling Microscope. The development of these two microscopes is considered a revolution in the atomic and molecular fields.

When talking of AFM, it captures precise images by moving a nanometer sized tip across the surface of the image. The STM captures images using quantum tunneling.

Of the two microscopes, the Scanning Tunneling Microscope was the first to be developed.

Unlike the STM, the probe makes a direct contact with the surface or calculates the incipient chemical bonding in AFM. The STM images indirectly by calculating the quantum degree tunneling between he probe and sample.

Another difference that can be seen is that the tip in AFM touches the surface gently touches the surface whereas in STM, the tip is kept at a short distance from the surface.

Unlike the STM, the AFM does not measure the tunneling current but only measures the small force between the surface and the tip.

It has also been seen that the AFM resolution is better than the STM. This is why AFM is widely used in nano-technology. When talking of the dependence between force and distance, the AFM is more complex than the STM.

When Scanning Tunneling Microscope is normally applicable to conductors, the Atomic Force Microscope is applicable to both conductors and insulators. The AFM suits well with liquid and gas environments whereas STM operates only in high vacuum.

When compared to STM, the AFM gives a more topographic contrast direct height measurement and better surface features.

Summary

1. AFM captures precise images by moving a nanometer sized tip across the surface of the image. The STM captures images using quantum tunneling.

2. The probe makes a direct contact with the surface or calculates the incipient chemical bonding in AFM. The STM images indirectly by calculating the quantum degree tunneling between he probe and sample.

3. The tip in AFM touches the surface gently touches the surface whereas in STM, the tip is kept at a short distance from the surface.

4. AFM resolution is better than the STM. This is why AFM is widely used in nano-technology.

5. When Scanning Tunneling Microscope is normally applicable to conductors, the Atomic Force Microscope is applicable to both conductors and insulators.

6. The AFM suits well with liquid and gas environments whereas STM operates only in high vacuum.

7. Of the two microscopes, the Scanning Tunneling Microscope was the first to be developed.

Advantages


AFM has several advantages over the scanning electron microscope (SEM). Unlike the electron microscope which provides a two-dimensional projection or a two-dimensional image of a sample, the AFM provides a three-dimensional surface profile. Additionally, samples viewed by AFM do not require any special treatments (such as metal/carbon coatings) that would irreversibly change or damage the sample. While an electron microscope needs an expensive vacuum environment for proper operation, most atomic force microscopy modes can work perfectly well in ambient air or even a liquid environment. This makes it possible to study biological macromolecules and even living organisms. In principle, AFM can provide higher resolution than SEM. It has been shown to give true atomic resolution in ultra-high vacuum (UHV) and, more recently, in liquid environments. High resolution AFM is comparable in resolution to scanning tunneling microscopy and transmission electron microscopy.
Disadvantages
A disadvantage of AFM compared with the scanning electron microscope (SEM) is the single scan image size. In one pass, the SEM can image an area on the order of square millimeters with a depth of field on the order of millimeters. Whereas the AFM can only image a maximum height on the order of 10-20 micrometers and a maximum scanning area of about 150×150 micrometers. One method of improving the scanned area size for AFM is by using parallel probes in a fashion similar to that of millipede data storage.

The scanning speed of an AFM is also a limitation. Traditionally, an AFM cannot scan images as fast as a SEM, requiring several minutes for a typical scan, while a SEM is capable of scanning at near real-time, although at relatively low quality. The relatively slow rate of scanning during AFM imaging often leads to thermal drift in the image making the AFM microscope less suited for measuring accurate distances between topographical features on the image. However, several fast-acting designs were suggested to increase microscope scanning productivity including what is being termed videoAFM (reasonable quality images are being obtained with videoAFM at video rate: faster than the average SEM). To eliminate image distortions induced by thermal drift, several methods have been introduced.

AFM images can also be affected by hysteresis of the piezoelectric material and cross-talk between the x, y, z axes that may require software enhancement and filtering. Such filtering could "flatten" out real topographical features. However, newer AFMs utilize closed-loop scanners which practically eliminate these problems. Some AFMs also use separated orthogonal scanners (as opposed to a single tube) which also serve to eliminate part of the cross-talk problems.


Related Solutions

Compare and contrast scanning tunneling microscopy (STM) and atomic force microscopy (AFM)? List at least two...
Compare and contrast scanning tunneling microscopy (STM) and atomic force microscopy (AFM)? List at least two advantages and two disadvantages for both methods. Please reference at least one source in your discussion.
Compare and contrast scanning tunneling microscopy (STM) and atomic force microscopy (AFM)? List at least two...
Compare and contrast scanning tunneling microscopy (STM) and atomic force microscopy (AFM)? List at least two advantages and two disadvantages for both methods. Please reference at least one source in your discussion. (It may be a textbook.)
Discuss the use of Atomic Force Microscopy (AFM) and Resonance Raman spectroscopy for determining the sequence...
Discuss the use of Atomic Force Microscopy (AFM) and Resonance Raman spectroscopy for determining the sequence of ink- writing on paper. Include an outline of how the AFM signal is generated.
B._____ Determine the high-resolution structure of a mitochondrion in cross section Atomic force microscopy (AFM) Light...
B._____ Determine the high-resolution structure of a mitochondrion in cross section Atomic force microscopy (AFM) Light microscopy, standard Light microscopy with differential interference contrast (DIC) Scanning electron microscopy (SEM) Transmission electron microscopy (TEM) Fluorescence microscopy, standard Laser scanning confocal microscopy (LSCM) Live cell imaging of GFP-tagged protein Fluorescence resonance energy transfer (FRET)
321312 What scientific 3213 information 321can be obtained by spin-polarized scanning tunneling microscopy that cannot be...
321312 What scientific 3213 information 321can be obtained by spin-polarized scanning tunneling microscopy that cannot be obtained via the spin unpolarized equivalent. Please support your answer by reference(s)
compare and contrast protein import into the ER and into the nucleus. List at least two...
compare and contrast protein import into the ER and into the nucleus. List at least two major differences in the mechanisms, and speculate why the ER mechanism might not work for nuclear import and vice versa.
Compare optical microscopy and standard scanning electron microscopy. -Describe 4 main advantages SEM can have over...
Compare optical microscopy and standard scanning electron microscopy. -Describe 4 main advantages SEM can have over optical microscopy when applied to structural engineering materials, and also mention 2 advantages that optical microscopy may have. - You want to investigate the fracture surface of a metallic alloy for structural applications. discuss the relative advantages and drawbacks of using SEM in BEI mode, SEM in SE mode and optical microscopy.
Explain in your own words the working of scanning electron microscope and Atomic Force microscope. In...
Explain in your own words the working of scanning electron microscope and Atomic Force microscope. In two paragraphs one for each. Include references if used.
Using the paper, “Multiparametric Atomic Force Microscopy Imaging of Biomolecular and Cellular Systems”, describe what is...
Using the paper, “Multiparametric Atomic Force Microscopy Imaging of Biomolecular and Cellular Systems”, describe what is meant by “Multiparametric AFM”.  Describe the impact and advantages of this approach. (Acc. Chem. Res. 2017, 50, 924−931)
Choose two different types of microscopy and compare/contrast them in detail.  If you were looking at a...
Choose two different types of microscopy and compare/contrast them in detail.  If you were looking at a typical liver cell using the two different types of microscopy, what structural details and organelles would be visible?   Compare and contrast DNA and RNA, including details of structure and function. What is protein modification?  Describe three examples of protein modification, as well as how the protein modification affects protein activity. How do you measure an enzyme’s performance? Describe how a competitive inhibitor and a non-competitive...
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT