Instrumental effects in the electron loss spectra from surfaces due to the use of LEED optics

Abstract

The use of a conventional retarding grid LEED-Auger apparatus to record low energy loss spectra from single crystal surfaces has been shown to produce spurious structure in the region within approximately 10 eV from the elastic peak. With the aid of miniature electron guns mounted on the crystal manipulator this structure was shown to arise from transmission effects at the retarding grids when a collimated monoenergetic beam of electrons traverses a limited number of retarding grid meshes. This effect was attributed to an uneven distortion of the electron trajectories due to the use of woven mesh in the manufacture of the grids. It was concluded that low energy loss spectra from single crystal surfaces which are free of this kind of instrumental artifact may be ensured with the incident electrons at normal incidence and at an energy which is sufficiently low so that all LEED beams are excluded from the analysis. Under these conditions the loss spectrum from a W(100) surface contained two broad losses at 2.7 and 5.2 eV which were attributed to interband transitions.