Rotational Epitaxy of Chemisorbed K Monolayers on Cu(001)

The structure change of incommensurate potassium monolayers on low-dislocation-density copper (001) has been observed at 330 K by low-energy electron diffraction. The orientation angle was found to increase uniformly from 3.3^∘{} to 6.0^∘{} when the potassium interatomic spacing was varied from 4.72 to 4.57 {}. The existence of rotational epitaxy, observed previously for physisorbed rare-gas monolayers, has been demonstrated for an alkalimetal monolayer on a metal surface.