EXTENDED FINE-STRUCTURE IN ELASTICALLY SCATTERED ELECTRON-SPECTRA - NATURE AND APPLICATION TO STRUCTURE-ANALYSIS

Extended fine structure (EFS) has been observed in elastically scattered electron (ESE) spectra. EFS has been observed in the energy range up to 2000 eV, its effect being not related to the thresholds of excitation of inner atomic levels. It has been shown that the EFS at electron energies above 100-200 eV can be described in the terms of a kinematic model of diffraction. Evidence of this is the dependence of the Fourier-spectra maxima on scattering angle. The interatomic distances determined from analysis of the EFS in terms of the kinematic model are in good agreement with literature data for all materials studied. The EFS in the low-energy region of the EFS-spectra is due, in our opinion, to multiple electron scattering effects. These multiple scattering effects reveal themselves as additional maxima in the Fourier-spectra of the ESE EFS.