Reading the Criss-Crossed Lines TEM

Transmission electron microscopy (TEM) is also used to visualize materials using electrons. Samples must be thin enough that the electrons transmit through them and then onto a detector below the sample. TEM can be used to look at the morphology of materials and also probe the crystalline properties. When crystals are present the electrons are diffracted, similar to what occurs with XRD. The diffracted electrons provide a picture with lines crisscrossing each other, and the lines represent the crystal lattice. 

The distance between the lines can be measured to determine the d-spacing (see Chapter 18). Not unlike SEM, the sample must be placed in an ultra-high vacuum (UHV) environment because the mean free path of electrons in air is very short. 

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