LAYER-BY-ATOMIC-LAYER DESORPTION OF CS FROM CU(111)/CS OBSERVED VIA PHOTOEMISSION

For Cs on Cu(111) the work function is found to depend on the Cs thickness for coverages less than three atomic layers. The magnitude of the work function variation is as predicted for a free-electron-like quantum well. The photo-yield observed for a photon energy slightly above the threshold for photoemission can be used as a measure of the adsorbed amount. Via the yield, the thermal desorption of the first three atomic layers can be followed layer-by-atomic- layer. The desorption energy differs by around 35 meV between the second and third layer.