Development of Total-Reflection Angle Soft X-ray Spectroscopy combined with RHEED

该项目的研究人员之一Ino发现，在观察反射高能电子衍射（RHEED）的模式时，可以检测到从只有一层的金属薄膜发出的全反射角的x射线共振线。他将这种新的表面分析方法命名为“RHEED-全反射角x射线光谱学（RHEED- traxs）”。RHEED- traxs是一种同时观察RHEED图案和分析表面化学计量学的强大方法。此外，通过改变电子的入射角和x射线的提取角来分析薄膜的深度分布是一种有用的方法。本项目的目的是在软x射线区域开发RHEED- traxs，即“RHEED-全反射角软x射线光谱（RHEED- trasxs）”，以显示该方法在表面化学分析中的实用性，并建议RHEED- trasxs的实际应用。1999年，我们在我们的机械车间生产了一个软x射线光谱仪的原型。该光谱仪采用带弯曲变间距凹槽的像差校正凹光栅对荧光x射线线进行分割。分裂的x射线通过多通道板检测，将x射线信号转换成可见光。真空室外的CCD摄像机通过一个观察口检测可见光。然而，在原型光谱仪系统上，信号太弱而无法检测。因此，我们计划改进光谱仪，将CCD相机放入真空中，由CCD相机直接探测x射线。2000年，我们买了CCD相机，可以放在真空中。我们也在我们的机械车间里，用真空CCD相机制作了改进的光谱仪。改进后得到了更好的频谱信噪比。然而，轫致辐射与光谱重叠。克服轫致应力将使我们能够将RHEED-TRASXS投入实际使用。

Ino, one of the investigators on this project, discovered that an X-ray resonance line emitted from a metal thin film with only a layer, at the total-reflection angle, can be detected on observing the pattern of reflection high-energy electron diffraction (RHEED). He named the new surface analysis method "RHEED - Total-Reflection Angle X-ray Spectroscopy (RHEED-TRAXS)". The RHEED-TRAXS is a powerful method to observe RHEED pattern and to analyze the stoichiometry of the surface simultaneously. Moreover, it is a useful method to analyze the depth profile of thin films by changing the incident angle of the electron and the extraction angle of the X-ray. The purpose of this project is to develop the RHEED-TRAXS at the soft X-ray region, i.e., "RHEED - Total-Reflection Angle Soft X-ray Spectroscopy (RHEED-TRASXS)", to show the usefulness of this method for chemical analysis of surface, and to suggest the practical use of RHEED-TRASXS.In 1999, We produced a prototype soft X-ray spectrometer in our machine shop. In this spectrometer, aberration-corrected concave grating with curved and variable spacing grooves was used to split the fluorescent X-ray lines. The splitted X-rays were detected by a multi-channel plate to change the X-ray signal into the visible light. The visible light was detected by a CCD camera out of the vacuum chamber through a viewing port. On the prototype spectrometer system, however, the signal was to weak to detect. Therefore, we planned to make an improved spectrometer to put a CCD camera into the vacuum, detecting the X-rays by the CCD camera directly.In 2000, We bought the CCD camera available to put in vacuum. We produced the modified spectrometer, using the CCD camera in vacuum, also in our machine shop. The modification brought us better S/N ratios of the spectrum. However, bremsstrahlung was overlapped with the spectrum. To conquer the bremsstrahlung will enable us to put the RHEED-TRASXS to practical use.