Meurer, Florian and Dolomanov, Oleg and Hennig, Christoph and Peyerimhoff, Norbert and Kleemiss, Florian and Puschmann, Horst and Bodensteiner, Michael (2022) Refinement of anomalous dispersion correction parameters in single-crystal structure determinations. IUCRJ, 9. pp. 604-609. ISSN 2052-2525
Full text not available from this repository. (Request a copy)Abstract
Correcting for anomalous dispersion is part of any refinement of an X-ray diffraction crystal structure determination. The procedure takes the inelastic scattering in the diffraction experiment into account. This X-ray absorption effect is specific to each chemical compound and is particularly sensitive to radiation energies in the region of the absorption edges of the elements in the compound. Therefore, the widely used tabulated values for these corrections can only be approximations as they are based on calculations for isolated atoms. Features of the unique spatial and electronic environment that are directly related to the anomalous dispersion are ignored, although these can be observed spectroscopically. This significantly affects the fit between the crystallographic model and the measured intensities when the excitation wavelength in an X-ray diffraction experiment is close to an element's absorption edge. Herein, we report on synchrotron multi-wavelength single-crystal X-ray diffraction, as well as X-ray absorption spectroscopy experiments which we performed on the molecular compound Mo(CO)(6) at energies around the molybdenum K edge. The dispersive (f') and absorptive (f'') terms of the anomalous dispersion can be refined as independent parameters in the full-matrix least-squares refinement. This procedure has been implemented as a new feature in the well-established OLEX2 software suite. These refined parameters are in good agreement with the independently recorded X-ray absorption spectrum. The resulting crystallographic models show significant improvement compared to those employing tabulated values.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | X-RAY-DIFFRACTION; SCATTERING FACTORS; ABSORPTION; ATOM; REFLECTION; anomalous dispersion; resonant scattering; diffraction spectroscopy; correction of the crystallographic model; synchrotron |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Central Analytical Services |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 15 Feb 2024 12:55 |
| Last Modified: | 15 Feb 2024 12:55 |
| URI: | https://pred.uni-regensburg.de/id/eprint/57660 |
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