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

在本研究中，我们发现多层样品的白光x射线反射率的测量是表征多层材料（正在申请专利）的有力工具，并且x射线反射率在x射线波导现象中呈现伪对称模式。这种表面分析方法是基于能量高于临界能量的x射线会反射，而能量低于临界能量的x射线会在界面处折射的物理现象。存在类似的表面分析方法，但由于入射的强x射线直接撞击探测器窗口，存在x射线探测器饱和的问题。在本研究中，我们避免了饱和，因此本方法作为一种实际应用的表面分析方法是非常有效的。我们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开放，可以免费下载。在非等角反射处测量x射线反射率时，能谱有向低能量侧偏移的趋势，这在理论上已经得到了成功的再现。因此，可以通过测量随入射角变化的能谱来表征表面。我们还制作了一种使用电池的便携式x射线分析仪，并成功地分析了被分析物表面的ppm级元素。伪对称模式为何可观测是一个开放问题；伪对称图案类似于所谓的米田翼，这与表面粗糙度密切相关。因此，伪对称图案可能具有表面粗糙度的信息。综上所述，我们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，利用表面行x射线波引导穿过表面和界面。

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.