SURFACE FERMI CONTOURS OF POTASSIUM ADSORBED W(011)

The Fermi contours for the surface-localized states of potassium adsor bed W(011) and the work function changes as a function of the potassiu m dose time are investigated using angle-resolved ultraviolet photoemi ssion spectroscopy (ARUPS). Similar to hydrogen covered W(011), rapid attenuations of the hole-orbit states are observed for potassium adsor ption. However, the electron-orbit states are not shifted to higher bi nding energies as much as those of hydrogen covered W(011). These resu lts show that the Fermi contours of potassium covered W(011) are not e xpanded much in comparison with those of hydrogen covered W(011).