Auger electrons are a type of electron emitted from an atom when an inner-shell electron is ejected. This process occurs when an atom absorbs energy, often from X-rays or gamma rays, causing an electron to be knocked out of its inner shell. The vacancy left behind can lead to the emission of an Auger electron as other electrons transition to fill the gap, releasing energy in the form of kinetic energy. These electrons are named after the French physicist Pierre Auger, who discovered the phenomenon in the early 20th century. Auger electrons are important in various fields, including materials science and medical imaging, as they can provide information about the elemental composition and electronic structure of materials.