Kinetic energy of the freed electron

Plasma, also called the fourth state of matter, is a partially or fully ionized gas containing electrons, ions and neutral atoms or molecules, where the atoms have so much kinetic energy that the valence electrons are freed by atomic-level colhsions [51]. Peebles [52] describes a plasma gas as containing a few parts per million of ions, 2 20% free radicals and a large amount of extremely energetic vacuum-ultraviolet light. 

E11.10(b) Energy is conserved, so when the photon is absorbed, its energy is transferred to the electron. Part of it overcomes the binding energy (ionization energy) and the remainder is manifest as the now freed electron s kinetic energy. 

The electron freed from the atom acts like any other moving charged particle. It may cause ionization of another atom if its energy is high enough. It will interact with matter, lose its kinetic energy, and finally stop. Fast electrons produced by ionizing collisions are called 8 rays. 

Photoemission from a solid is a surface event. In figure 2, a photon absorption event is shown. In solid materials, x-rays can be absorbed over a considerable depth (several microns) into the solid surface depending on the photon energy (3). When photoemission occurs, as shown, the electron is freed from an atom in the crystal lattice and moves freely in the conduction band of the material. In most materials, electron-electron interactions readily occur resulting in a loss of electron kinetic... 

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