The structure ofAl(111)-K(3 3)R30 determined by LEED: stable and metastable adsorption sites
It is found that the adsorption of potassium on Al(111) at 90 K and at 300 K both result in a (\u221a3 \xd7 \u221a3)R0\xb0 structure. Through a detailed LEED analysis it is revealed that at 300 K the adatoms occupy substitutional sites and at 90 K the adatoms occupy on-top sites; both geometries have hitherto been considered as very unusual. The relationship between bond length and coordination is discussed with respect to the present results, and with respect to other quantitative studies of alkali-metal/metal adsorption systems.