Polarization-dependent phase and amplitude interference effects in theL2,3surface extended x-ray absorption fine structure

The phase and amplitude of the surface extended x-ray absorption fine structure above $L_2$ and $L_3$ edges is shown to be significantly affected by an interference term. This term exhibits a different phase and a different polarization dependence of the amplitude than the leading term (pure $l=2\mathrm{}$ final state). Neglect of this term in the data analysis can lead to erroneous determinations of chemisorption sites and distances.