ABSTRACT
In analogy to visible optics the interaction of X-rays with small transparent structures above several nanometres size results in coherent scattering governed by wavelength, structural dimensions and shape, local phase shift and absorption. In contrast to optical conditions the refractive index of X-rays close to unity causes beam deflections into the same small angular region of several minutes of arc as does diffraction. Thus the resulting interferences are due to phase modulation due to the refractive index and the absorptive and Raleigh diffraction, both depending on the path length through matter.
