X-ray absorption spectra about the
Kedges of Ni, Cu and Ti have been measured at the Stanford Synchrotron Radiation Laboratory. The imaginary part of the atomic scattering factor f′′ was determined using the optical theorem and the real part f′ computed by the Kramers–Kronig dispersion relation. Methods for evaluating this integral as well as the effects on f′ of various experimental errors are investigated. The f′ results for Cu and Ni are compared to data from interferometry experiments.