Development of a surface analysis method by X-ray traveling waves using an X-ray wave guide

我们发现，多层膜样品的白色X射线反射率的测量是表征多层膜的有力工具（正在申请专利），并且X射线反射率对于X射线波导现象表现出伪对称模式。这种表面分析方法是基于能量高于临界能量的X射线将反射，而能量低于临界能量的X射线将在界面处反射的物理现象。存在类似的表面分析方法，但是它们具有X射线检测器饱和的问题，因为入射的直接强X射线撞击在检测器窗口上。在目前的研究中，我们已经避免了饱和，因此，本方法是非常有效的实际使用的表面分析方法。我们已经开发了一个计算机程序来分析实验数据，其源代码已经在网页上公开，可以免费下载。在非等角反射下测量X射线反射率时，能谱有向低能侧移动的趋势，这在理论上已被成功地再现。因此，可以通过测量随入射角变化的能谱来表征表面。我们还制作了使用电池的便携式X射线分析仪，并成功地分析了分析物表面上的ppm级元素。为什么伪对称图案是可观察的是一个开放的问题;伪对称图案类似于所谓的米田翼，这是密切相关的表面粗糙度。因此，伪对称图案可以具有关于表面粗糙度的信息。总之，我们已经开发了一种表面分析方法，通过比较X射线反射率的测量和理论计算，使用表面行波通过表面和界面引导的X射线。

We have found in the present research that the measurement of the white X-ray reflectivity for multilayer samples is a powerful tool to characterize multilayers (under patent application), and that the X-ray reflectivity exhibits pseudo-symmetric pattern for X-ray wave guide phenomena. This surface analysis method is based on the physical phenomena that X-rays higher energy than the critical energy will reflect, while X-rays lower energy than the critical energy will refract at the interface. Similar surface analysis methods exist but they have a problem of the saturation of the X-ray detector Because the incident direct strong X-rays impinge on the detector window. In the present research, we have avoided the saturation and consequently the present method is highly effective for the practical use as a surface analysis method. We have developed a computer program to analyze the experimental data, and the source code of it has been open in the Web page, and it can be freely downloaded. When the X-ray reflectivity is measured at the off-equiangular reflection, the energy spectrum tends to shift to the lower energy side, which has been successfully reproduced theoretically. Therefore the surface can be characterized by the measurement of an energy spectrum with the change of the angle of incidence. We have also made a portable X-ray analyzer using an electric battery, and succeeded to analyze ppm level elements on the analyte surface. The reason why the pseudo-symmetric pattern is observable is an open problem ; the pseudo-symmetric pattern resembles the so-called Yoneda wing, which is closely related to the surface roughness. Therefore the pseudo-symmetric pattern may have an information on the surface roughness. In summary, we have developed a surface analysis method by comparing the measurement of X-ray reflectivity and theoretical calculation, using surface traveling X-ray waves guided through the surface and interfaces.