Romanov V P, Ul'yanov S V
Department of Physics, St. Petersburg State University, Petrodvorets, St. Petersburg 198504, Russia.
Phys Rev E Stat Nonlin Soft Matter Phys. 2002 Feb;65(2 Pt 1):021706. doi: 10.1103/PhysRevE.65.021706. Epub 2002 Jan 23.
The consequent description of the x-ray scattering from the free standing smectic-A films is suggested. Calculations are based on the discrete model for the film dynamics. The scattering intensity temporal autocorrelation function <I(t)I(0)> is obtained within the framework of this approach neglecting the multiple scattering and refraction effects. It is shown that the behavior of this function crucially depends on the film thickness. In particular, in thin films containing less than 10(3) layers the time dependence of <I(t)I(0)> has damping oscillation character. This behavior is determined by an acoustic mode that describes the film motion caused by the action of the surface tension. For thick films containing more than 10(4) layers the dynamics of the intensity temporal autocorrelation function is determined either by an acoustic mode or by a wide spectrum of modes depending on the x-ray geometry. In both the cases the autocorrelation function is a relaxation one. The results obtained are compared with the experiments on the coherent soft and hard x-ray scattering.
本文提出了对独立的近晶 - A 膜的 X 射线散射的后续描述。计算基于膜动力学的离散模型。在忽略多重散射和折射效应的这种方法框架内，获得了散射强度时间自相关函数<I(t)I(0)>。结果表明，该函数的行为关键取决于膜的厚度。特别是，在包含少于 10³ 层的薄膜中，<I(t)I(0)>的时间依赖性具有阻尼振荡特性。这种行为由描述表面张力作用引起的膜运动的声学模式决定。对于包含多于 10⁴ 层的厚膜，强度时间自相关函数的动力学取决于 X 射线几何结构，由声学模式或宽模式谱决定。在这两种情况下，自相关函数都是弛豫型的。将所得结果与相干软 X 射线和硬 X 射线散射的实验进行了比较。
