Calculations on the effect of the surface potential barrier in LEED

The main effects of the surface potential barrier in LEED arise from strong internal reflection of diffraction beams for incidence conditions close to those for their grazing emergence. Near each grazing emergence condition, the details of LEED intensity profiles depend on the amplitude coefficient of internal reflection and hence on the shape of the surface potential barrier. Calculations of the amplitude coefficient for real one-dimensional barrier potentials with shapes specified by three parameters are reported. The calculations are done as a function of the energy associated with the surface-normal momentum component of the internally incident beam. The potential has the image form at large distances from the surface and joins smoothly to a quadratic at an intermediate distance. The results are tabulated and an interpolation formula is given so that the amplitude coefficient of reflection can be evaluated readily for potentials of the assumed form. Applications to the calculation of LEED intensity lineshapes are summarized.