New theoretical investigation resolving discrepancies of atomic form factors and attenuation coefficients in the near-edge soft X-ray regime

Reliable knowledge of the complex X-ray form factor and the photoelectric a ttenuation coefficient is required for crystallography, medical diagnosis, radiation safety and XAFS studies. Discrepancies between currently used the oretical approaches of 200% exist for numerous elements for X-ray energies from 1 to 3 keV. This work addresses key discrepancies and derives theoreti cal results in near-edge soft X-ray regions. DHF wave functions are employed and computational and convergence issues ar e of direct concern. Comparisons with simpler wave functions, including add itional relativistic corrections to the form factors, are insightful. The current result improves upon the theoretical uncertainty in these regio ns to an estimated standard deviation of 20-30%. (C) 2001 Elsevier Science Ltd. All rights reserved.