# When was the electronvolt first introduced?

When was the unit "electronvolt" (eV) first introduced, and by whom?

The definition of the eV requires the knowledge of the electron charge $e$, so it must have been introduced after 1909, the date of the famous oil drop experiment conducted by R. A. Millikan and H. Fletcher, in which, as far as I know, $e$ was measured for the first time.