The interaction of KCl with tungsten single crystal surfaces

The interaction of KCl vapor with W single crystal surfaces is studied with the aim of obtaining information on the adsorption of ionically bonded molecules. The atomically smoothest and roughest surfaces, (110) and (111), are used. The adsorbate is characterized by LEED, thermal desorption spectroscopy (TDS) and by photoemission experiments which can be related to known work function data. It is found that the adsorbate is undissociated on W(110) and to a large extent also on W(111) at room temperature and that no ordered structures are formed. Electron bombardment causes KCl dissociation and Cl desorption which is complete with sufficiently high electron doses. Close-packed K monolayers can be formed this way.