放射光による極微小単結晶の構造解析法の開発

在材料科学领域中，长期以来一直期望开发用于获得微米尺寸的结晶物质（诸如从地球或陨石获得的非常微小的矿物）的晶体学信息的设备。由于同步辐射（SR）的高强度，它可以用来处理这样小的样品，但即使在SR中，也要特别注意测量非常弱的衍射强度。在不使用SR的情况下，50微米的尺寸可能是衍射法检测样品的极限。衍射强度与样品体积成正比，微米级晶体的衍射强度约为<-5>上述极限值的10倍。因此，实验的噪音水平应尽可能低。如果噪声电平变得可以忽略不计，则可以通过调整测量时间来将信号连续地累积到期望的强度电平。为此，实验应在真空中用定晶法和很窄的准直X射线束进行，由于上述原因以及通过倒易空间原点的倒易行上的各布拉格反射强度相互叠加的事实，采用了劳厄法，劳厄照相机安装在光子工厂BL-4 B（距光源20 m），密封在真空中，安装在很窄的准直器中。该系统已发展到在环电流128 ~ 125 mA条件下，能在成象板上对直径为0.8 μ m的钼单晶进行50分钟的多次布拉格反射。得到的劳厄照片被认为是在良好的协议与计算模式。

In the field of material sciences, it has long been desired for developing the equipment to obtain crystallographic information of micrometer-size crystalline substances such as very minute minerals obtained from earth or meteorites. Synchrotron radiation(SR) could be a candi-date to deal with such a small specimen because of its high intensity.Even in the case of SR, special care should be paid for the measurement of very weak diffracted intensities. In the case not using SR, the size of fifty micrometers might be the limit for the specimen to be examined by diffraction method. The diffracted intensity is proportional to the volume of specimen, and that of micrometer sized crystal is estimated as 10^<-5> times of that of the limit mentioned above. The noise level of the experiment, therefore, should be as low as possible. If the noise level becomes negligibly small, the signal could be accumulated continually to the desired intensity level by adjusting measuring time. The experiment,for the purpose, should be carried out in vacuum with stationary crystal method and with very narrow collimated X-ray beam.The Laue method is employed by the above reason as well as the fact that the intensitiy of each Bragg reflection on a reciprocal row passing through the origin of the reciprocal space is superposed with each other, which also intensifies a diffraction spot on the photographic plate.The Laue camera is set up at BL-4B (located at 20 m from source point) of Photon Factory, sealed in vacuum and installed in very narrow collimater. The development of the system has been performed to the level at which several Bragg reflections of molybdenum single crystal with 0.8 micrometer in its diameter can be taken on the imaging plate for fifty minutes ex-posure with ring current from 128 to 125 mA. The obtained Laue photograph is found to be in good agreement with the calculated pattern.