Acoustically adjustable LiNbO3 double-crystal monochromator for synchrotron radiation

Abstract

First experiments with the acoustically controlled LiNbO3 double-crystal monochromator for synchrotron radiation have been performed on the diffraction beamline of the Brazilian National Synchrotron Light Laboratory. In order to modify x-ray optical properties of LiNbO3 crystals, 290 MHz surface acoustic waves were generated with the aid of interdigital transducers, fabricated on the polished crystal surfaces by using microelectronics technology. It was shown that by the appropriate choice of diffraction planes, the LiNbO3 double-crystal monochromator can be used for both high-flux and high-resolution applications. Surface acoustic waves allow adjustment of an angular width of diffraction profile to a divergence of the incident synchrotron radiation, optimizing matching conditions for x rays of different wavelengths. Diffraction measurements under surface acoustic wave excitation demonstrated that the parameters of the x-ray beam issuing from the monochromatization system are indeed acoustically controlled, providing a 2–2.5-fold broadening of the diffraction profile and a 1.5-fold gain in the maximum diffraction intensity.