Applications of Surface Science 13 (1982) 180 189 North-Holland Publishing Company THE ANALYSIS OF LEED FINE STRUCTURE P.J. JENNINGS, S.M. THURGATE and G.L. PRICE * School ofMathematical and Physical Sciences, Murdoch University. Murdoch, WestAustralia 6150, Australia LEED intensity curves at low primary beam energies exhibit surface harrier resonance fine structure. These resonances are due to the interference between electron waves diffracted by the crystal surface and waves internally reflected by the surface barrier. The resonance profiles may be analysed to test various theoretical models of the surface barrier and to obtain structuial details for adsorbate overlayers. We report recent studies on the (001) planes of Cu and Ni and discuss the information they provide about the structure of the metal/vacuum interface. 1. Introduction Low energy electron diffraction (LEED) is now well-established as the primary technique for structural studies of crystal surfaces. LEED pattern analysis provides details of surface and overlayer structure and LEED intensity analysis can yield pre- cise details of overlayer location and surface layer spacings. LEED intensity measurements and theoretical analysis are usually carried out with primary beam energies in the range of 50 250 eV. R-factor analysis is now be- ing widely used to compare measured and calculated curves and to refine structural parameters. LEED calculations are usually not carried out at low energies (<50 eV) because of a lack of knowledge about the energy dependence of the inner potential and the structure of the surface barrier. In principle LEED structural analysis should be easier at low energies because fewer beams and phase shifts are required to achieve convergence in the calculations. This paper describes progress with the analysis of the fine structure of LEED in- tensity curves at very low primary energies. 2. Surface barrier resonances For some years it has been known that LFED intensity curves at low energies * Present address: Telecom Australia Research Laboratories. Clayton. Victoria. Australia.