Effective magnetic quantum number and effective emitter–scatterer distance obtained from W 4f photoelectron diffraction induced by circularly polarized light on W(1 1 0)

Circular dichroism has been measured in the photoelectron diffraction of W 4f photoelectrons from W(1 1 0)1×1 clean surface. The forward-focusing peaks along symmetric axes in diffraction pattern rotate azimuthally in either counterclockwise or clockwise direction depending on light helicity around the incident light axis. Using the formula suggested by Daimon et al. [Jpn. J. Appl. Phys. 32 (1993) L1480] substituting measured rotation angles for the [1 0 0] and [1 1 1] peaks, we evaluated effective atomic distance between an emitter and a scatterer, after calculating effective magnetic quantum number as a function of the polar angle between directions of the incident light and the photoelectron. The results of the effective atomic distance longer than the nearest-neighbor distance for each forward-focusing direction suggest partial contribution to the forward-focusing peak by the scatterers behind the nearest neighbor, within a single scattering theory.