Spin dependence of electronic surface resonance scattering from W(100)

In polarized low energy electron diffraction (PLEED) from W(100) at energies of 2 to 9 eV and incident angles 15°< θ < 45°, we observe a spin-splitting of the resonance sequence of peaks which converge on the (01) beam threshold. For θ>26° the peak splitting to peak width ratio is approximately constant while for decreasing θ≤26° it increases. An anomalous spin-up-only peak appears at small θ. The nature of the spin dependent splitting is discussed within the four-beam layer multiple scattering approximation.