GRAZING-INCIDENCE DIFFRACTION ON LINBO3 UNDER SURFACE-ACOUSTIC-WAVE EXCITATION

X-ray diffraction under grazing incidence and exit angles, a(i) and a( f) (GID) was used for the first time to study longitudinal displacemen ts in surface acoustic waves (SAW) propagating on LiNbO3 single crysta ls. The a(1)-resolved (006)-diffraction spectra have been investigated as a function of the applied voltage for SAW excitation. Substantial increase of diffraction intensity (up to 100%), accompanied by a sharp ening of the diffraction profile was found in these measurements. The most pronounced influence of SAW on GID was observed for both the a(i) and a(f) near the critical angle a(c). The diffraction rods were succ essfully simulated in the framework of dynamical diffraction theory, u sing only one SAW-related parameter, namely an additional Debye-Waller factor responsible for reduction of the scattering amplitude. This he uristic approach allowed to explain all experimental effects and serve d to estimate the amplitudes of the longitudinal component of the SAW in the near-surface layer of LiNbO3.