A suite of programs for calculating x-ray absorption, reflection, and diffraction performance for a variety of materials at arbitrary wavelengths

Abstract

One of the most useful characteristics of synchrotron radiation is the wide spectral distribution of the source. For applications involving tuned monochromatic beams it is often helpful to predict the x-ray optical characteristics of a sample or the beam line optics at a particular wavelength. In contrast to this desire stands the fact that tabulated values for the optical parameters of interest are generally available only at wavelengths corresponding to typical x-ray tube sources. We have developed a suite of fortran programs which calculate photoabsorption cross sections and atomic scattering factors for materials of arbitrary, uniform composition or for arbitrary layered materials. Further, the suite includes programs for calculation of x-ray diffraction or reflection from such materials. These programs are of use for experimental planning, data analysis, and predictions of performance of beam line optical elements.

The TP0796 Lipoprotein of Treponema pallidum Is a Bimetal-dependent FAD Pyrophosphatase with a Potential Role in Flavin Homeostasis

“…3G). A strong peak at the Me2 site was observed as well as a smaller peak at the AMP phosphate that is due to the small amount of anomalous signal expected for phosphorus at this energy (48). No anomalous signal was observed at the Me1 site, which is probably a reflection of the high affinity of this site for a non-exchangeable metal ion that does not absorb x-rays at the incident wavelength.…”

The synthesis and characterisation of coordination and hydrogen-bonded networks based on 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoic acid

“…23 These datasets were processed using the XDS software suite, 24 with anomalous dispersion corrections for the non-standard wavelength applied using Brennan and Cowan data. 25 All structures were solved using direct methods with SHELXS 26 and refined on F 2 using all data by full matrix least-squares procedures with SHELXL-97 27 within OLEX-2 28 or through the X-Seed interface. 29 …”

The Non-Resonant Magnetic X-ray Scattering Cross Section of MnF2. 2. High-Energy X-ray Diffraction at 80keV

“…For a measurement of the charge reflections, the diffracted beam has to be attenuated to avoid saturation of the detector. We employed an absorber of 2mm Pb and 18mm Fe to measure the charge reflections, which leads to a transmission of 1.1 x 10 -6 for 80 keV, 3.9 × 10 -2 for 240keV (third harmonic) and 0.103 for 320keV (fourth harmonic) after Brennan & Cowan (1992). Since for a completely closed wiggler gap the energy spectrum extends to very high energies, the saturation of the detector due to higher harmonics can be a serious problem.…”

“…For MnF 2, it is/Z80ke v --1.484 cm -1 . /z has been calculated using the values for Mn and F from the program ABSORPTION (Brennan & Cowan, 1992).…”