International
Tables for Crystallography Volume H Powder diffraction Edited by C. J. Gilmore, J. A. Kaduk and H. Schenk © International Union of Crystallography 2018 |
International Tables for Crystallography (2018). Vol. H, ch. 2.5, p. 123
Section 2.5.2.4.1. Diffraction unit vector in diffraction space and sample space^{a}Bruker AXS Inc., 5465 E. Cheryl Parkway, Madison, WI 53711, USA |
In 2D-XRD data analysis, it is crucial to know the diffraction-vector distribution in terms of the sample coordinates S_{1}, S_{2}, S_{3}. However, the diffraction-vector distribution corresponding to the measured 2D data is always given in terms of the laboratory coordinates X_{L}, Y_{L}, Z_{L} because the diffraction space is fixed to the laboratory coordinates. Fig. 2.5.8 shows the unit vector of a diffraction vector in both (a) the laboratory coordinates X_{L}, Y_{L}, Z_{L} and (b) the sample coordinates S_{1}, S_{2}, S_{3}. In Fig. 2.5.8(a) the unit vector h_{L} is projected to the X_{L}, Y_{L} and Z_{L} axes as h_{x}, h_{y} and h_{z}, respectively. The three components are given by equation (2.5.5). In order to analyse the diffraction results relative to the sample orientation, it is necessary to transform the unit vector to the sample coordinates S_{1}, S_{2}, S_{3}. Fig. 2.5.8(b) shows the same unit vector, denoted by h_{s} projected to S_{1}, S_{2} and S_{3} as h_{1}, h_{2} and h_{3}, respectively.