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![[Figure 2]](he3170fig2mag.jpg)
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Figure 2
Size–divergence diagram for X-ray scattering. The horizontal axis represents the size of the specimens to be studied and the required divergence of the beam is shown on the left-hand vertical axis. The right-hand axis gives a corresponding unit-cell dimension. This would be on the limit of being resolved with an X-ray beam of this divergence using 1 Å radiation. The same argument applies when focusing on the detector. In this case, the angular resolution of the diffracted beam is determined by the size of the X-ray beam focus at the detector and the specimen size determined by the divergence of the X-ray beam from detector to sample. Three sources are shown as curved lines having emittances of 7, 2 and 0.04 mm mrad. These are full width at half-maximum (2.35σ) values. The flux from these sources in a 0.1% bandpass is shown. This diagram is, therefore, a slice at a bandpass of 0.1% through the 3D size–divergence–bandpass diagram. • The requirements for some representative samples or experiments. ▪ Source and focus for a proposed undulator beamline. ♦ Positions of two detectors for collecting data at 3 Å resolution. |
![[Figure 2]](he3170fig2.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
