Surface morphology changes due to adsorbates and due to electron bombardment

Low index surfaces are in most cases stable even after adsorption, whereas vicinal surfaces may be only stable without or even with adsorbates. Since these phenomena are rather frequently reported, some carefully studied examples are discussed here, to show the importance of the effect and possible reasons for the sometimes dramatic morphology changes. Metals on semiconductors and metals are well studied and therefore the best examples for the present purpose. Since vacancies at the surface may act as point defects in a similar way, f-centers on NaCl are included into the discussion.