INSTRUMENTAL EFFECTS OF RETARDING GRIDS IN A LEED APPARATUS

We have studied the characteristics of the retarding grids in a low energy electron diffraction apparatus by measuring the impact spectra of a tungsten (100) crystal with 66 to 200 eV electron beams. Our results indicate that the retarding field method when properly adjusted is useful for analyzing scattered electrons of energy loss which is small compared to the beam energy. At large energy loss, however, field penetration and scattering from grids may contribute considerably to the measured secondary electron energy distribution which makes the measurement less reliable. © 1969 The American Institute of Physics.