Diffraction by Single Crystals, Crystal Powders and Fibres

3 Diffraction by Single Crystals, Crystal Powders and Fibres 

The diffraction pattern recorded on a film from a planar array irradiated with monochromatic light would be a series of spots, corresponding to the various orders of diffraction from the regular lines comprising the equivalent of various diffraction gratings. 

The crystal plane (2h, 2k, 21) has half the spacing of the Qi, k, 1) plane and thus the conditions for fulfilment of the Bragg equation (equation 4.2) are the same for first order diffraction from the 2h, 2k, 21) plane as for second order diffraction from the (h, k, 1) plane, and usually all observed diffractions are treated as first order. 

Historically the oldest is the Laue method, in which white X-rays containing many frequencies impinge on a stationary single crystal. The result is a 

Continuous, white Single crystal No Spots Laue diffraction pattern 

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