Interpretation of LEED pattern

Interpretation of LEED pattern

Figure 3 shows the Ewald's sphere for the case of normalSRF750 incidence of the primary electron beam, as would be the case in an actual LEED setup. It is apparent that theM5661P pattern observed on the fluorescent screen is a direct picture of the reciprocal lattice of the surface. The size of the Ewald's sphere and henceTIM5359-60SL the number of diffraction spots on the screen is controlled by the incident electron energy. From the knowledge of the reciprocal latticeRT9362 models for the real space lattice can be constructed and the surface can be characterized at least qualitatively in terms of the surface periodicity and the point group. FigureHC5160 5.a shows a model of an unreconstructed (100) face of a simple cubic crystal and the expected LEED pattern. The spots are indexed according to the values of h and k.