Effect of the ultrasonic frequency on the multiple X-ray scattering from a LiNbO3 crystal modulated by a surface acoustic wave

Abstract

The effect of multiple scattering on the formation of the scan curves for a crystal modulated by a surface acoustic wave (SAW), depending on the ultrasonic frequency, has been investigated in the frame work of the dynamical theory of X ray diffraction. A model of a Rayleigh surface wave has been analyzed as applied to X ray diffraction with allowance for the transverse and longitudinal elastic lattice strains. Using the example of the 127° Y' cut of the LiNbO 3 crystal, it is established that the effects of multiple scattering can be neglected for ultrasonic frequencies above 650 MHz; this finding significantly simplifies the numerical cal culations of X ray diffraction from a crystal modulated by a short wavelength SAW. A comparative quantita tive analysis of the experimental data on synchrotron scattering from the 127° Y' cut of a LiNbO 3 crystal mod ulated by a 952 MHz SAW have been performed, both taking into account and neglecting the effects of mul tiple scattering. It is shown that the computation time can be reduced by 2 to 3 orders of magnitude.

The dynamical theory of diffraction in a crystal modulated by a surface acoustic wave in the case of spatially restricted X-ray beams

“…The system of coupled equations (5) corresponds to the description of dynamical multiple X-ray diffraction in crystals (Authier, 2001). The criterion for considering multiple diffraction was investigated by Punegov & Roshchupkin (2012). In the case of short-wave modulation, a single-order mode is valid, while equations (5) are written as…”

“…With regard to theoretical studies, we should note the development of the statistical dynamical theory of X-ray diffraction in a crystal modulated by a SAW (Nesterets & Punegov, 2004;Punegov & Nesterets, 2005;Punegov et al, 2007Punegov et al, , 2010 and the application of this theory to the analysis of the results of double-and triple-axis diffractometry (Punegov, 2003;Punegov et al, 2010;Punegov & Roshchupkin, 2012;Punegov, 2012).…”

X-ray diffraction by phase diffraction gratings

“…5), a system of satellite diffraction peaks denoted by m and n is formed in the reciprocal space. Neglecting the multiwave interaction between diffraction orders (Punegov & Roshchupkin, 2012), a system of equations for satellites denoted as ðm; nÞ is…”