International
Tables for Crystallography Volume G Definition and exchange of crystallographic data Edited by S. R. Hall and B. McMahon © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. G, ch. 3.3, p. 127
Section 3.3.8.4. Energy-dispersive X-ray detection^{a}NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8562, USA |
For energy-dispersive X-ray diffraction, an X-ray detector is placed at a fixed value of and a diffractogram is measured on a multichannel analyser. The channel number is then calibrated to yield photon energies. From the energy and angle, a d-spacing or Q value is calculated for each diffraction point. Note that energy, d spacing or Q are not the experimental independent variable. Rather, they result from processing, since calibration information is required. The calibration equation should be described in _pd_calibration_conversion_eqn.
In Example 3.3.8.4, the nominal setting is 6.5°, but the actual position (determined by prior calibration) is 6.6071°, so the difference is indicated using a _pd_calib_2theta_offset value (see Section 3.3.4.3).