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.

X-ray diffraction from perfect silicon crystals distorted by surface acoustic waves

“…The main result of the interaction of X-rays with SAWs is the rise of very strong diffraction satellites in the re¯ectivity measurements. Several experiments have already been carried out on Bragg diffraction on SAWs in lithium niobate crystals (Zolotoyabko & Polikarpov, 1998;Polikarpov et al, 1999;Tucoulou et al, 2000). Very recently, SAW-induced diffraction satellites were observed in synchrotron experiments with GaAs-based SAW devices (Sauer et al, 1999).…”

Ultrasound adjustable Laue-Laue double-crystal x-ray monochromator

“…As a consequence, the total throughput of the monochromator system will be correspondingly higher. It could be further increased by USW [2][3][4][5][6][7][8], although USW application to non-piezoelectric crystals like Si and Ge is technically more challenging.…”

“…An application of ultrasonic wave (USW) to nearly prefect crystals in combination with x-ray diffraction attracts growing attention due to the possibility, to introduce in a crystal, a periodic deformation variable in a pre-defined reproducible way. This approach is considered promising in application to x-ray diffraction studies of electronic materials [2,3], measurements of weak acoustic fields in acoustooptical devices [4][5][6], construction of synchrotron radiation monochromators [7,8], diffraction modulators [9], quarterwave plates [10] and for control of x-ray beams in time and § Corresponding author.…”