kiloelectronvolt

Kiloelectronvolt (keV) is a unit of energy equal to 1,000 electronvolts. The electronvolt (eV) is the energy gained by the charge of an electron when accelerated through a potential difference of one volt. In SI terms, 1 eV is 1.602176634×10^-19 joule, so 1 keV is 1.602176634×10^-16 joule. The prefix kilo denotes a factor of one thousand, and 1 keV is 0.001 MeV. The kiloelectronvolt is not an SI base or derived unit but is accepted for use with the SI.

KeV is widely used in physics and engineering to express energies in the X-ray range and for particles in the keV energy regime. X-ray energies, spectroscopy, and detector calibration often report photon energies in keV or in keV-edge references. Electron microscopes operate with accelerating voltages that yield electrons with kinetic energies in the tens to hundreds of keV. In nuclear and particle physics, keV-scale energies describe low-energy transitions and detector responses, and in astrophysics, X-ray spectra of hot plasmas commonly span keV energies.

Related units include the electronvolt, the megaelectronvolt (MeV), and the gigaelectronvolt (GeV). 1 keV equals 1,000 eV and 0.001 MeV. The keV remains a practical unit for describing energies where X-rays or low-energy nuclear and particle processes occur, and it is widely used across disciplines, often distinguished from higher-energy scales by context.