Maximum probability of elastic electron backscattering from surfaces of amorphous and polycrystalline solids

The theory of elastic electron backscattering from disordered condensed matter predicts complex behavior in the energy dependence of the monitored intensity. For high atomic number elements, numerous maxima are predicted. The dependence of maxima positions on the detection angle is discontinuous, with numerous branches. The present paper provides the experimental proof confirming the validity of the theory. Extensive experimental studies of elastic backscattering were performed for platinum and gold. At energies above 400 eV, two separated branches of maxima were found, in excellent agreement with theory. It has been found that the complex structure of the energy dependence of the backscattered intensity is closely related to the energy dependence of the elastic scattering cross sections. This proves that the elastic backscattering is (i) predominantly caused by the interaction between electrons and the atom cores, and (ii) dominated by the first large angle scattering event.