Structure determination white radiation

The Laue method (using white radiation) has not yet been used for a de novo virus structure determination. Whilst this method continues to have potential for stud)dng d)mamic events it compounds the problem of spot resolution and will only be feasible with detectors with greater resolution than is furnished by current CCD detectors. 

The types of radiations that are used in structural crystallography are mainly x-rays, neutrons, and electrons. The use of electrons is still difficult for structure determination but can be a useful tool for the detection of structural transitions (see Section X). White or monochromatic x-ray beams can conveniently be obtained from sealed tubes, rotating anode generators, or synchrotron sources [5], with relative flux magnitudes on the order of 1, 10, >100, respectively. The first two x-ray sources are continuous and are generally designed to produce almost monochromatic beams, while synchrotron radiation is pulsed and white. Neutron sources are comparatively much weaker and are either continuous (nuclear reactor) or pulsed (spallation source [6]). 

Figure 2.5. The schematic of a typical x-ray emission spectrum, for clarity indicating only the presence of continuous background and three characteristic wavelengths Kai, Kaj, and Kp, which have high intensities. The relative intensities of the three characteristic spectral lines are approximately to scale, however, the intensity of the continuous spectrum and the separation of the Kai/Kaj doublet are exaggerated. Fine structure of the Kp spectral line is not shown for clarity. The vertical arrow indicates the shortest possible wavelength of white radiation, Xsw, as determined by Eq. 2.4.

Fig. 3.32. Spectral composition of white radiation according to G. H. Stout and L. H. Jensen, in X-ray Structure Determination...

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