Cross Sections

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The cross sections computed here are based on form-factor approximation and optionally include corrections utilizing angle-independent anomalous scattering factors. Cross sections for unpolarized, linearly-polarized and circularly-polarized photons can be computed.

One of three separate form-factor tabulations can be selected for use in the calculation:

  • modified relativistic form factors,
  • relativistic form factors,
  • nonrelativistic form factors.
We have independently computed the modified relativistic form factors and relativistic form factors used in these calculations on a dense grid to assure accurate interpolation to intermediate values. These values agree well with available published tabulations (Schaupp et al, 1983; Hubbell and Ø verbø , 1979). The nonrelativistic form factors are taken from the tabulation of Hubbell et al. (1975).

Optionally, our evaluation of angle-independent anomalous scattering factors can be included with the modified relativistic form factors, or the relativistic form factors.

For more information see

"Validity of Form-Factor, Modified-Form-Factor and Anomalous-Scattering-Factor Approximations in Elastic Scattering Calculations," by Lynn Kissel, B. Zhou, S. C. Roy, S. K. Sen Gupta and R. H. Pratt, Acta Crystallographica A51, 271-288 (1995).

"Small-Angle Rayleigh Scattering of Photons at High Energies: Tabulations of Relativistic HFS Modified Atomic Form Factors," D. Schaupp, M. Schumacher, F. Smend, P. Rullhusen and J. H. Hubbell, J. Phys. Chem. Ref. Data 12, 467-512 (1983).

"Relativistic Atomic Form Factors and Photon Coherent Scattering Cross Sections," J. H. Hubbell and I. Ø verbø , J. Phys. Chem. Ref. Data 8, 69-105 (1979).

"Atomic Form Factors, Incoherent Scattering Functions, and Photon Scattering Cross Sections," J. H. Hubbell, W. J. Veigele, E. A. Briggs, R. T. Brown, D. T. Cromer and R. J. Howerton, J. Phys. Chem. Ref. Data 4, 471-538 (1975); errata ibid. 6, 615-616 (1977).

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Information date: August 8, 2000 lk