FFAST.jl
X-ray Mass Attenuation and Absorption Factors
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Implements in Julia an interpolation scheme for Chantler's FFAST X-Ray Form Factor, Attenuation, and Scattering Tables as downloaded from the NIST FFAST web site
Users should refer to the NIST website for a detailed discussion of the provenance of these values. In general, however, they are based on a self-consistent Dirac-Hartree-Fock framework. Interpolated values of the f1 and f2 components of the form factors, the photoelectric attenuation coefficient for the atom, [µ/ρ]pe, the coherent and incoherent attenuation coefficient, [μ/ρ]ci, the total mass absorption coefficient [μ/ρ]tot and the value for the K-shell, [µ/ρ]K are made available through exported functions.
In addition, exported functions provide access to other elemental data items including the mean atomic weight, the cross-section factors, the nominal density, E(V), the relativistic correction factors and the nuclear Thompson correction.
The tabulations are discussed in two references:
- Theoretical Form Factor, Attenuation and Scattering Tabulation for Z=1-92 from E=1-10 eV to E=0.4-1.0 MeV J. Phys. Chem. Ref. Data 1995 (https://physics.nist.gov/PhysRefData/FFast/Text1995/contents1995.html)
- Detailed Tabulation of Atomic Form Factors, Photoelectric Absorption and Scattering Cross Section, and Mass Attenuation Coefficients in the Vicinity of Absorption Edges in the Soft X-Ray (Z = 30-36, Z = 60-89, E = 0.1 keV-10 keV), Addressing Convergence Issues of Earlier Work J. Phys. Chem. Ref. Data 2000 (https://physics.nist.gov/PhysRefData/FFast/Text2000/contents2000.html)