Development of X-ray Acoustic Spectrometer Using Synchrotron Radiation

本课题组利用同步辐射X射线源研制了X射线声学谱仪（XAS）装置和方法。1.装置研制采用驻极体的X射线声学（XA）探测器（XA池）。X射线斩波器、第一离子室、该XA室和第二离子室在光学台上顺序对准。XA单元安装在X-Z脉冲平台上，以便获得用于成像的样品的二维扫描。该级的扫描和锁相放大器及两个皮安表的数据采集均由微机采用GP-IB基准线进行调节。最后组装并建立了一套可自动运行的XAS系统，并开发了一种新的检测器，我们称之为“光学麦克风”，它可以光学地检测振动膜的运动，以提高灵敏度。成功地开发了一种新的检测方法，该方法使用压电传感器，PVDF聚合物膜，该传感器也是敏感的，并且可以在真空下使用。2.方法的发展该方法在材料的非破坏性亚表面评估能力方面是独特的。为此，将X射线调制成半脉冲形状并照射到样品上。结果发现，延迟信号分量是源于亚表面材料。通过X射线束的扫描，揭示了材料在表面下的分布。我们称这种方法为“半脉冲XAS法”。还开发了使用聚焦X射线束的XA-EXAFS光谱和XA成像，并成功地应用于各种模型样品，以发现原子结构分析和材料三维无损评价的潜力。

Apparatus and methods for X-ray Acoustic Spectroscopy (XAS) which was innovated by our research group were developed using synchrotron radiation X-ray source.1.Development of ApparatusAn X-ray acoustic (XA) detector (XA cell) using a electret was developed. X-ray chopper, 1st ion chamber, this XA cell and 2nd ion chamber were aligned in sequence on a optical stage. The XA cell was mounted on the X-Z pulse-stage in order to get the 2 dimensional scanning of the sample for imaging. The scanning of this stage and data acquisition from a lock-in amplifier and the two pico-ampere meters were regulated by a microcomputer using GP-IB bas line. A total system for XAS which can be operated automatically was finally assembled and established.A new detector which detects the movement of a vibrating membrane optically, we call "optical microphone" was also developed for more sensitivity. One more new detection method using a photopyroelectric sensor, PVDF polymer film, was successfully developed which is also sensitive and can be used under vacuum.2.Development of MethodologyThis method is unique in the ability of non-destructive sub-surface evaluation of materials. For this purpose, X-ray was modulated in semi-pulse shape and irradiated on to the samples. It was found that the delayed signal components was originated from a sub-surface material. By scanning of X-ray beam, the distribution of materials under the surface was revealed. We call this method as "Semi-Pulse XAS method". XA-EXAFS spectroscopy and XA-imaging using focused X-ray beam were also developed and applied successfully to various model samples to find the potentials for analysis of atomic structure and 3-dimensional non-destructive evaluation of materials.