Energy Resolution of Crystal Spectrometers

The resolution of crystal spectrometers is traditionally expressed as the resolving power, which is the inverse of the energy resolution  

It should be pointed out that the X-ray detector used with the crystal spectrometer need not have an extremely good energy resolution, because it is the resolution of the analyzing crystal that determines the spectroscopic capabilities of the system, not that of the detector. The X-ray counter may be a proportional counter or a Si(Li) detector. 

Example 12.1 What is the energy resolution of an X-ray crystal spectrometer for 6-keV X-rays using a crystal with d = 0.15 nm and AO = 0.3°  

One can improve the resolution by decreasing AO or using a crystal with a smaller interplanar distance. 

The energy range over which crystal spectrometers can be used is determined, in principle, from the Bragg condition (Eq. 12.22) and the requirement that 0 sin 0 1. Using Eq. 12.22 and assuming 0 n 0.5°, d = 0.2 nm, and 

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