backscattering electrons

[Kit]

what is meant by backscattering electrons? :confused:

i am confused by this and secondary electrons....

thx for answering :biggrin:

[ZapperZ]

what is meant by backscattering electrons? :confused:

i am confused by this and secondary electrons....

thx for answering :biggrin:

The problem here is that you did not put your question in the context that you are seeing these things. Remember that in physics, certain things have different exact meanings in different areas.

If I based those on what I think they are, based on what I'm familiar with (secondary emission process, SEM, etc), then:

(i) backscattering electrons are the primary electrons that you detect that were "reflected" off the material, i.e. these are the same incident electrons - they simply bounced off the surface of the material and came back almost into the same direction the came from. One signature of these electrons is that they have the same energy as the primary.

(ii) secondary electrons are electrons that came from the material itself AFTER the absoption of the primary electron. So you shoot a bunch of primary electrons at a material, the primary get absorbed, and electrons came out. The secondary electrons may be MORE in number than the primary, depending on the energy of the primary electrons and the secondary emission yield (SEY) of the material. If a material has a SEY of 4 at a particular energy, then a primary electron hitting the material at that very same energy can cause the emission of 4 secondary electrons. Of course, these secondary electrons have energies way lower than the incident primary. This technique is most often used in SEM, Auger spectroscopy, etc.

Zz.