DYNAMICAL LOW ENERGY ELECTRON DIFFRACTION ANALYSIS FOR Cs/GRAPHITE(0001)-(√3×√3)R30°SURFACE

A model incorporating(Cs-A-ABAB)stacking with Cs atoms chemisorbed in hollow sites 2.70A above the top graphite plane and the two top graphite layers shear-shifted to AA stacking and expanded to a separation of 3.85A is the most reliable structure for Cs/graphite(0001)-(√3×√3)surfaces.The coexisting diffraction pattern including the diffraction ring and another set of (√3×√3) diffraction pattern which has a 30°rotation angle with respect to the normal(√3×√3)R3O°diffraction pattern could be explained.We consider this strueture to be in a prein ter cal ation state.