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Inelastic interactions (scattering), result in the transfer of energy from primary electrons to the atoms of the sample, and this energy exchange is limited to atomic electrons, rather than nuclei… Inelastic scattering decreases the kinetic energy of the bombarding electron; meanwhile the deviation of its path is very small… Bremsstrahlung (continuum) X-rays, deceleration of primary electrons (with primary energy E0) in the Columbic field of the nucleus, a type of ‘braking’ effect…. i.e. as to pass though the stronger electric filed, close to nuclei, it will suffer a “quantum jump” to a low energy state, which will make emission of X-ray photon, and it would be all possible energy up to E0… Secondary electron, (<50 eV, normally around 2-6 eV, larger than sample’s work function) excitations result to loose bound valence electrons, which are promoted from the valence band to the conduction band in insulators and semiconductors, or directly from the conduction band in metals. … Auger electrons (Auger effect, give surface chemical composition) as an atom excited by electron bombardment, it may “release” its energy by ejecting an electron (rather than by characteristic X-ray emission)… Characteristic X-ray emission is that generated by the relaxation of an excited atomic state arising from an inner shell vacancy. The transition of an electron from one of the outer shells produces an X-ray phonon with an energy (or wavelength) that represents the difference between the two states…. It will be covered in details in next week EDS part…. Long-wavelength electromagnetic radiation in the visible, ultraviolet and infrared regions… SE(I) directly by primary electron SE(II) by backscattering electron as they escarp from surface… Signals such as secondary electrons (SE) and Auger electrons come from only a very tiny portion of the total interaction volume, since they lack the energy to travel large distances… Only these SE electrons that originated within a few nanometer of the surface are able to escape from sample…. SE has much lower energy than BSE (which used for design of different detectors…)… covered in details in the following Lecture… Elastic interactions (scattering), Elastic interactions affect the trajectories of the primary beam electrons inside the specimen without altering their kinetic energies. An elastic collision occurs when a primary electron is within range of the electrostatic field of an atomic nucleus. 1. Rutherford scattering (Coulomb filed around nuclei, large than 90 degree) 2. Multiple scatterings, typically at low angle 2◦–5◦ per scattering event, after multiple scatterings it is possible to escape from sample surface at180 ◦ … conduction band (for metallic materials) valence band with different banding (for semiconductor and insulator) mean free path, average distance covering by a particle (photon, atom, electron etc.) between subsequent impacts… e.g.