On the extraction of surface barrier potentials from threshold effects in LEED: saturation on Cu(001) revisited

The authors give a critical discussion of the extraction of the surface barrier potentials from LEED threshold effects as introduced by Dietz, McRae and Campbell (1980) for Cu(001). They show that their approximation, together with experimental and theoretical procedure, introduce an effective phase for the total-internal-reflection coefficient at the barrier from which the correct barrier shape cannot be extracted. Without the trick of a discontinuous barrier shape, the authors' correct analysis gives a better description than the empirical analysis. There remains, however, some discrepancy and the extraction of the Cu(001) barrier shape still needs both more experimental data and more theoretical studies for which the authors have specified the LEED framework.