U. Korte et G. Meyerehmsen, DYNAMICAL RHEED FROM DISORDERED SURFACES - SHARP REFLECTIONS AND DIFFUSE-SCATTERING, Surface science, 298(2-3), 1993, pp. 299-306
A formalism for the dynamical calculation of RHEED from disordered sur
faces, based on perturbation theory, is presented. The scattering into
the sharp reflections is determined by the periodic part of the poten
tial. The diffuse scattering arises from transitions between dynamical
ly calculated scattering states in the periodic potential part and the
non-periodic part is treated as a perturbation. For atoms being place
d on equivalent lattice sites relative to the periodic potential part,
a pseudo-kinematical treatment for the diffuse scattering is possible
. Conventional structure factors have to be multiplied by. dynamically
calculated atomic scattering amplitudes so that the statistics of the
disorder can be treated independently from the dynamical calculations
. Comparisons between theory and experiment are given for Pt(Ill) and
Pt(110), including thermal diffuse scattering. Further model calculati
ons for the diffuse RHEED from disordered adsorbate layers demonstrate
that the corresponding scattering distribution depends strongly on th
e position of the adsorbate relative to the substrate. This may open t
he use of RHEED in the field of structure analysis of disordered adsor
bate systems.