Multiple Guinier cameras

The novel type of Guinier camera described in this paper is characterized by a combination of several cameras in a compact unit using a single focusing monochromator and a single film, and by the disposition of the camera relative to the monochromator in such a manner that [alpha]-doublet diffraction lines coincide for a [theta] value of, say, 15°. In this way an exceptionally high resolving power is obtained in a considerable range of glancing angles, centred about this value, which contains the most selective lines for analytical purposes. The line width in the respective cameras is discussed, and the conclusion is reached that in the significant region [theta] < 30° there is no appreciable difference between the outer and the middle cameras of the unit. With a view to comparison purposes, the line shift for the outer cameras is also calculated; it appears to be of little consequence. Finally, short descriptions of a twofold and of a fourfold camera are given.