2.3 Transmission Electron Microscopy and Quasi-Elastic Light Scattering

 Transmission electron microscopy (TEM) and quasi-elastic light scattering (QELS) were

used in Chapters 6 and 7 to determine the shape and size of the core-shell nanocapsules and of

the molecularly imprinted nanoparticles.

 Electron microscopes use a beam of highly energetic electrons to examine objects on a

very fine scale and can yield information such as sample topography, morphology, composition,

or crystallinity.90 The electron source first forms a beam of electrons that are accelerated toward

the specimen with a positive electrical potential. The beam is focused onto the sample, and

various interactions can occur inside the irradiated sample, affecting the electron beam as shown

in Figure 2-6.


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Figure 2-6. Specimen interactions in electron microscopy.'"
 The electrons of interest in TEM are only the unscattered electrons, even though the other

types of electrons can be of interest for other applications. These unscattered electrons are


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