The removal of an electron from the surface of an atom - that is, the ionization of the atom - means a fundamental structural change in its surface layer.

Die elektrischen Quanten. Career
Stark worked in various positions at the Physics Institute of his alma mater until 1900 when he became an unsalaried lecturer at the University of Göttingen. (Sonderabdruck aus 'Annalen der Physik' 4.