SecondaryElectrons:When the incident electron hits the sample, surface area of thesample are very much vulnerable to get that electron, they absorb the electronthat comes in but they themselves release some electrons which is calledsecondary electrons.
The electron that goes inside which is absorbed is primaryelectrons. So the electrons they release from them their selves that are calledsecondary electrons. The interaction range is only few nanometres and it is lowenergy electrons.Using secondary electrons we can study the surface topography and composition of the molecules. Backscatteredelectrons:Backscattered electrons are another type of signal that comesout from the sample surface when the incident beam of electrons bombards to thesample. Some electrons will be reflected whichever electron comes in.
In simplewords back scattered electrons are primary beam of electrons scattered back outof sample. It comes from the surface and from the deeper within the specimen.The Backscattered electrons can be used to study the atomic number and topography and evencomposition of the molecules can be determined. Characteristic X-rays:When the incident beam of electrons strikes the surface of thespecimen, some amount of electrons are also absorbed, so no electrons comesout, they absorb the electrons. Some region of the specimen can absorb theelectrons, that absorption can give rise to specific x-ray radiation.
In simplewords, as an effect of interaction between the sample and the electron beam,the primary electron will be slowed down or break and do the conservation ofenergy and the electron give off an x-ray to maintain its momentum.The X-rays can tell us about the Thickness and atomic composition of the molecules. AugerElectrons:This is one of the types of signal produced when the electronbeams strikes the sample surface. As a result of interaction photons aregenerated and the photons hit an electron from the outer energy levels withhigh energy, auger electrons are generated. Surfaceatomic composition can be studied using Auger electrons.