Surface-Sensitive XAFS in the Hard X-ray Region with Sub-Monolayer Sensitivity

Surface-sensitive X-ray absorption fine structure (XAFS) with sub-monolayer sensitivity based on grazing-incidence fluorescence detection is reported. The efficiency of fluorescence detection increased by more than two orders of magnitude by combining a multipole wiggler with a multi-element Si(Li) solid-state detector. The capability of the present technique for structural studies of surfaces and buried interfaces in the hard X-ray region was demonstrated by As K-edge XAFS studies of the InP(001) surface exposed to AsH₃ flow. The results indicated that ~0.1 monolayer As atoms are incorporated into the surface replacing the P atoms.