X-ray diffraction effect from surface acoustic waves traveling on a deposited multilayer.

We investigate the x-ray diffraction effects from surface acoustic waves (SAW) traveling along a multilayer. The diffraction intensity distribution depends on the incidence angle and the multilayer SAW (MLSAW) amplitude. Particularly, a small departure deviating from the Bragg incidence angle at a certain amplitude will produce a larger variation of the intensity distribution. This shows that the diffraction intensity from MLSAW has an extremely high sensitivity to the Bragg incidence angle, which is different from a SAW traveling along a solid surface without deposited layers. By carefully analyzing the relationship between the intensity distribution I and the incidence angle theta, the corresponding analytic expression of the intensity distribution is theoretically derived. Our theoretical prediction is in great agreement with the experimental results previously obtained. A theoretical model that can be applied to study the x-ray diffraction effect from MLSAW is developed. The extremely high sensitivity to the Bragg angle will help us in acousto-optic instrument research with MLSAW.