LEED Beam Broadening as a Result of Sputtering Damage

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Abstract
Investigations of sputtering damage based only on changes in LEED intensities are unable to distinguish between lattice distortions resulting from bombardment atoms imbedded in the lattice and localized structural defects such as vacancies. Such a distinction can be made on the basis of beam broadening. The observed beam broadening due to bombardment of a clean annealed (100) nickelsurface with 500‐eV argon ions can be accounted for by assuming that a strain of 0.05 is introduced by occluded argon atoms. As a result of the finite beam width, plots of the intensity of the beam as a function of electron energy are affected by the mechanics of recording and reducing the data. It is shown that the correct intensity can be obtained regardless of beam width by superimposing plots of collector current versus electron energy for all values of the collector angle.