The arrangement of atoms within a nanoparticle can be critically important for it’s performance. Therefore, apart from being super-cool, atomic-resolution imaging is also quite useful.
You can obtain information such as how the atoms are packed together and the spacing between each atom to help in identifying the structure. This is important for semiconductor applications where breaks and defects in the crystal can affect electron transport within the material.
The picture below is a cool image I took on the TEM at the nanoscale showing the atomic arrangement of a lanthanide phosphate nanorod.
The nanorod is positioned such that we are seeing down perfectly on columns of atoms (the dots). This is quite special (and lucky) as any slight variation in angle would have created lines instead of dots. As a result, I would have lost some information on the atomic arrangement. The spacings marked out, together with the angles can be used to identify the material (but you need to have some idea as to what it is so you can compare with models).
Notice the pattern is continuous and doesn’t change angle suddenly. This suggests that the nanorod is a single, perfectly arranged crystal. Nanoparticles are generally arranged as a single crystal as it’s energetically preferred. Now you could look at this in two ways: either as another example of nature’s beauty, or that atoms are just so darn lazy.
Warning: This part has big scary words.
What you are seeing is an interference pattern created by the atoms – it is technically incorrect to say that the white dots or black dots are actually atoms. There are other techniques on the TEM where you can directly visualize where the atoms are. An example is HAADF-STEM (High-Angle Annular Dark-Field – Scanning Transmission Electron Microscopy) (Phew, what a mouthful).
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so how does one have to remember the words that are very long?????
haha normally you don’t have to – that’s what google is for!