Use of spin-polarized LEED rotation curves to study disordered surfaces: W(001)−(1 × 1) and W(001)−2H(1 × 1)

Extensive data sets of spin-polarized low energy electron diffraction (SPLEED) rotation curves from the clean W(001)−(1 × 1) and hydrogen-saturated W(001)−(1 × 1) and W(001)−2H(1 × 1) surfaces are presented. These represent the first simultaneous LEED measurements of two components of the electron spin polarization and diffracted intensity on any system. These measurements should be more sensitive to the disorder of the surface layer of clean W(001)−(1 × 1) than traditional LEED I–V curves at normal incidence for three reasons: the large scattering angles enhance intralayer scattering relative to interlayer scattering; electron spin polarization measurements are particularly sensitive to intensity minima where diffuse scattering from disorder is relatively important; and the data set is a comparative study of ordered and disordered surfaces. The data are in qualitative agreement with a smaller surface layer contraction and a greater degree of order on the hydrogen-saturated surface compared to the clean surface. These results suggest that detailed SPLEED calculations are justified to test and quantify these indications.