Grazing incidence X-ray absorption spectroscopy of near surface regions: Possibilities and limitations

The application of the grazing incidence X-ray absorption spectroscopy (GIXAS) to the investigations of near surface regions of layer systems is discussed. Starting with transmission standards, GIXAS spectra for different detection modes were calculated as functions of the grazing angle, layer composition and surface/interface roughness. For systems consisting of only one layer that participates to the XAFS signal, the fine structructure is a linear superposition of the fine structures in the real and the imaginary part of the energy dependent refractive index. The surface roughness less than about 2 nm does not significantely reduce the surface sensitivity of the method. An example of near surface structure determination for an oxidized metal surface is given.