photoionisation

Photoionisation is the physical process in which an incident photon ejects one or more electrons from an atom, ion or molecule.The ejected electrons, known as photoelectrons, carry information about their pre-ionised states. For example, a single electron can have a kinetic energy equal to the energy of the incident photon minus the electron binding energy of the state it left. Photons with energies less than the electron binding energy may be absorbed or scattered but will not photoionise the atom or ion.
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