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    B: 4 of 4

This simulation models the interaction of high energy electrons with atoms of aluminium. The incoming primary (red) electron can be elastically scattered, losing very little energy, or it can undergo an inelastic scattering process.

The interactions modelled here include the excitation of inner shell electrons, the creation of plasmons and interactions with single valence electrons.

In the simulation, each incoming primary electron is shown separately after you click on the "Next electron" button. Subsequent relaxation of inner shell excited atoms may occur by the emission of an X-ray or an Auger electron.

We call the high energy electron coming from some external source such as an accelerator or an electron microscope the primary electron. Here it is coloured red to distinguish it from the electrons already at equilibrium in and around the atom.

Some questions which you might like to ask yourself about the simulation after running it for ten or twenty primary electrons:

  1. Consider the relative frequency with which the various scattering processes occur in the simulation. Are these as you would expect?
  2. Consider the relative numbers of X-ray and Auger electrons which have been emitted following K-shell excitations. Are these what you would expect for aluminium?
  3. What happens after an L-shell electron is knocked out by the primary electron? (This is not shown on the simulation.)
  4. The model treats electrons as particles. Would you want to modifiy the model in any way to take into account the wave nature of electrons?

To answer these questions, you may need to refer to other sources such as the recommended books.


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