Potassium absorption into the graphite (0001) surface: Intercalation

Evaporation of potassium onto the graphite (0001) surface results in intercalation when potassium is evaporated from a hot molecular-beam source onto a graphite sample with high surface step density. Low-energy electron-diffraction (LEED) and Auger-electron spectroscopy (AES) studies indicate that after initial absorption of potassium from a hot source, the graphite surface structure became A/ABAB⋯ stacking (where "/" indicates potassium), with a disordered potassium layer intercalated between two graphite layers which have been shear shifted and expanded to a separation of 5.35 {}. Further adsorption of potassium onto the sample surface results in AA/ABAB⋯ stacking with 5.35 {} separation between each of the three top graphite layers, indicating the formation of a stage-1-like intercalate within the surface region although with disordered potassium. These structures indicate that potassium intercalates into the graphite (0001) surface in a layer-by-layer fashion.