Development of X-ray Acoustic Spectrometer Using Synchrotron Radiation

利用同步辐射X射线源研制了本课题组创新的X射线声谱(XAS)装置和方法。1.装置的研制研制了一种驻极体X射线声(XA)探测器。X射线切割器、第一电离室、该XA池和第二电离室在一个光学平台上依次对准。将XA池安装在X-Z脉冲工作台上，对样品进行二维扫描成像。这一级的扫描和来自锁定放大器和两个皮安计的数据采集由一台微型计算机通过GP-IB基线进行调节。最终组装并建立了一个可以自动操作的XAS系统，并开发了一种新的光学检测振膜运动的探测器，我们称之为光学麦克风，以提高灵敏度。另一种新的基于光电传感器的检测方法--PVDF聚合物薄膜也被成功地开发出来，该方法同样灵敏，可以在真空下使用。2.方法学的发展这种方法在材料的亚表面无损评价方面是独一无二的。为此，X射线被调制成半脉冲形状并照射到样品上。结果表明，延迟信号分量来源于一种地下材料。通过X射线扫描，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”。XA-EXAFS光谱和聚焦X射线XA成像也被发展起来，并成功地应用于各种模型样品，以发现在原子结构分析和材料三维无损评价方面的潜力。

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.