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Last modified 3 years ago Last modified on 09/06/12 15:39:02

pyFPRIME and ABSORB

This project contains two python GUI programs used for computing approximate x-ray scattering cross sections (f, f' and f") for individual elements using the Cromer & Liberman algorithm (reference: Acta Cryst. 1981 v.A37, p.267). FPRIME computes and plots elemental scattering factors. ABSORB computes scattering and absorption for a given composition and makes an attempt to estimate density as well. ABSORB can be also accessed as a web utility (see http://11bm.xray.aps.anl.gov/absorb/absorb.php).

Note that these computations are performed for elements between Li - Cf and in the X-ray wavelength range 0.05 - 3.0Å (4.13-248 keV) using the Cromer & Liberman algorithm and orbital cross-section tables. Note that the Cromer - Liberman algorithm fails in computing f' for wavelengths < 0.16 Å (> 77.48 keV) for the heaviest elements (Au-Cf) and fails to correctly compute f', f" and mu for wavelengths > 2.67 Å (< 4.64 keV) for very heavy elements (Am-Cf).

To obtain a copy of the files see the trunk directory in Trac or use subversion to download from https://subversion.xray.aps.anl.gov/pyFprime/trunk/. This software runs in Windows, Linux and Mac OS X, provided a working python interpreter with WxPython and Matplotlib is installed. We have used the Enthought Python Distribution.

Contact: Robert B. Von Dreele