electron volt

elektronivoltti puhekieltä A unit for measuring the energy of subatomic particles; the energy equal to that attained by an electron moving through a potential difference of one volt. Equivalent to 1.6022 x 10-19 joules.
2011, (w) & Jeff Forshaw, The Quantum Universe, Allen Lane 2011, p. 158n:

To get a feel for the size, the energy required to completely liberate an electron from the ground state of a hydrogen atom is 13.6 electron volts.