Using diffraction losses in the single-crystal X-ray optics for precise determination of its cell parameters and tuning the monochromator

A way has been developed to measure the unit-cell parameters of a single crystaljust from an energy scan with X-rays, even when the exact energy of the X-raysis not well defined due to an error in the pitch angle of the monochromator. Theprecision of this measurement reaches da/a 1 105 . The method is based onthe analysis of diffraction losses of the beam, transmitted through a single crystal(the so-called ‘glitch effect’). This method can be easily applied to anytransmissive X-ray optical element made of single crystals (for example, X-raylenses). The only requirements are the possibility to change the energy of thegenerated X-ray beam and some intensity monitor to measure the transmittedintensity. The method is agnostic to the error in the monochromator tuning andit can even be used for determination of the absolute pitch (or 2) angle ofthe monochromator. Applying the same method to a crystal with well knownlattice parameters allows determination of the exact cell parameters of themonochromator at any energy