The Bragg law modified for X-ray diffraction from a bent crystal in the backscattering mode

It is demonstrated for X-ray diffraction from a bent crystal in the backscattering mode that the Bragg angle in the crystal can differ from the value in vacuum by ∼10⁻². This difference exceeds the angular width of the region of total reflection for the CuKα radiation backscattered from the (220) plane of a silicon single crystal. The Bragg law modified with allowance for the refraction and crystal bending is presented.