International
Tables for Crystallography Volume C Mathematical, physical and chemical tables Edited by E. Prince © International Union of Crystallography 2006 
International Tables for Crystallography (2006). Vol. C, ch. 6.3, p. 600

In the wavelength regime associated with anomalous scattering, where the refractive index becomes complex, its imaginary component contributing an additional term to the absorption.
is the scattering factor for ideal elastic scattering. The dispersion corrections f′ and f′′ are related to the absorption since (James, 1962; Wagenfeld, 1975) That is, the dispersion corrections are determined by the absorption cross sections. The relationships (6.3.2.2) and (6.3.2.3) can be used in measuring absorption coefficients, as described in Section 4.2.4 . The dispersion terms change rapidly near the absorption edge, especially on the shortwavelength side. The changes are anisotropic, sensitive to structure and to the direction of polarization. Details are given by Templeton & Templeton (1980, 1982, 1985).
In nearperfect crystals, the changes near the absorption edge are also sensitive to temperature (Karamura & Fukamachi, 1979; Fukamachi, Karamura, Hayakawa, Nakano & Koh, 1982). The effective absorption coefficient can also be altered by the Borrmann effect (Azaroff, Kaplow, Kato, Weiss, Wilson & Young, 1974).
References
Azaroff, L. V., Kaplow, R., Kato, N., Weiss, R. J., Wilson, A. J. C. & Young, R. A. (1974). Xray diffraction, pp. 282–284. New York: McGrawHill.Fukamachi, T., Karamura, T., Hayakawa, K., Nakano, Y. & Koh, F. (1982). Observation of effect of temperature on Xray diffraction intensities across the In K absorption edge of InSb. Acta Cryst. A38, 810–813.
James, R. W. (1962). The optical principles of the diffraction of Xrays, pp. 135–192. Ithaca: Cornell University Press.
Karamura, T. & Fukamachi, T. (1979). Temperature dependence of Xray reflection intensity from an absorbing perfect crystal near an absorption edge. Acta Cryst. A35, 831–835.
Templeton, D. H. & Templeton, L. K. (1980). Polarized Xray absorption and double refraction in vanadyl bisacetylacetonate. Acta Cryst. A36, 237–241.
Templeton, D. H. & Templeton, L. K. (1982). Xray dichroism and polarized anomalous scattering of the uranyl ion. Acta Cryst. A38, 62–67.
Templeton, D. H. & Templeton, L. K. (1985). Tensor optical properties of the bromate ion. Acta Cryst. A41, 133–142.
Wagenfeld, H. (1975). Theoretical computations of Xray dispersion corrections. Anomalous scattering, edited by S. Ramaseshan & S. C. Abrahams, pp. 13–24. Copenhagen: Munksgaard.