Published online by Cambridge University Press: 10 February 2011
Bragg reflection (001) of high-quality crystal of ammonium acid phthalate (2d = 52.28 A˚) is investigated in the region of CK absorption edge. First order reflection for this crystal is forbidden. Due to anisotropic additions, it appears only near CK edge. Two-crystal optical scheme was used for the measurement of the crystal reflectivity. As shown, the change of crystal azimuth in X-ray spectrometer leads to ability to control the resolution. Rotation effects of X-ray beam polarization on 90° angle is considered for the forbidden reflection.