Oscillatory deviations from Porod's law in the intensities scattered by some glasses

The oscillatory deviations with respect to the Porod asymptote, observed in the small-angle X-ray intensities scattered by some selenium ruby glasses, are explained in terms of a finite discontinuity of the second-order derivative of the correlation function. The best fit of the intensity allows the value of the discontinuity to be determined as well as the point at which it occurs. The physical implications of these results are discussed.