We usually use TEM for the image analysis of metal and polymer-based NPs. In the case of hybrid NPs, we would like to correlate the results obtained from TEM and AFM analysis. The size distribution of NPs obtained from both instruments is varied. Is it unlikely?
M. Nuruzzaman Khan "The size distribution of NPs obtained from both instruments is varied. Is it unlikely?". Yes it will vary.. AFM is like 'touch' whereas TEM data is by 'sight'.. and in this case TEM data is more reliable..
Hi M. Nuruzzaman Khan
I recommend your answer Sridhar Vadahanambi
You may perform both the AFM and TEM of the same sample and can tally the results. You may perform the XRD analysis, and tally the average particle size with the other results.
Regards
Hi
The TEM image of polymer-hybrid NPs is basically the shadow of the transmitted electron through the prepared polymer-hybrid NPs sample. In contract,the AFM image of the polymer-hybrid NPs is basically the profile of the free electrons on the free surface of the sample. Since both TEM and AFM techniques work by different means, therefore,it is expected to have the size distribution of NPs to vary.
Any micros(nano)copic profile depends on the intrinsic resolution of the tecnique, which is essentially convoluted with the particles size. In the AFM, the response is a convolution of the tip size and the particle size, and the tip size becomes a more important consideration the smaller the particles are.
I would use the same specimen for both techniques (TEM grid for AFM) because specimen preparation could introduce additional errors. And of course I would pay attention to Hugh J Byrne comment.
Hello Sridhar Vadahanambi
Arnab Mukherjee
Khaled J. Habib
Hugh J Byrne
Vladimir Dusevich
Thank you all for the brainstorming discussion.
I do prefer both of the instruments as they deliver precise results.
We do need to choose carefully best methods for each analysis.
Thank you again for those suggestions.
Regards,
Nuruzzaman
For me the answer is " both techniques can offer very precise results", But with certain limitations in both cases.
TEM is a really powerful if not the most powerful nano visualization technique, but thinking in the nature of the interactions between electrons and sample, maybe some times TEM polymer visualization can be difficult. What I mean, the polymer -organic material-is almost invisible for the electrons (low atomic number materials produce a very low contrast images) in a transmission microscope, the contrast is sometimes low, and many times not good enoug to define correctly the shape or contour of the polymer particle, or sometimes could be confusing.
Then if you ask for the most precise method to measure metal Nanoparticles probably I´ll answer very quickly TEM, but for hybrid systems may be AFM could be a good or better option.
AFM microscope works as a blind person reconstruc the universe around, with the stick (tip) the person "touch" the surfaces, and with the brain (feedback unit and PC) we reconstruct the sampled surfaces. In AFM as for a blind person, the material from which the surface is made is of no interest (in terms of topography). The blind person does not care if the obstacle is made of plastic or metal, they care about the topography of it, touching/sampling the ground to avoid accidents, the same happens in the AFM with the topography, since it does not matter what material the surface is but its topographic characteristics, the tip is sensing the topographic relief no matter what it is made of. When measuring Polymer Metal hybrid NPs, the AFM will measure the contour of NPs regardless of what material they are made of. If the contour (the most external layer of the NPs) is organic, using AFM could be a clear advantage. As mentioned in one of the answers, it is important to select the tip type, tip diameter or radius , the aspect ratio, and the number of lines to obtain a good result.
In any case if you are lucky enough to be able to measure your sample with both techniques, they will offer you complementary results that will allow you to better understand their nature, topography and characteristics.
If it is the dimension, i will suggest TEM. I think you can use AFM if you are looking to assess or explore the surface area
I would say TEM will be more accurate in terms of nanoparticle size. The wavelength of electrons in the TEM beam will be in the pm range, while the smallest probe for AFM you can use will yield AFM resolution in the Ang-nm range.
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