Crystallographic studies on interplanetary dust particles

行星际尘埃粒子（IDPs）被认为保存着太阳系早期的信息。美国宇航局/约翰逊航天中心收集了IDPs，并通过电子显微分析和电子显微镜观察的方法对其进行了初步调查。由于它们的尺寸，x射线衍射法尚未应用于它们。因此，晶体学信息是未知的。在光子工厂（PF），利用同步辐射（SR）和劳厄方法，开发了一种分析亚微米尺寸晶体的系统。为了获得IDPs的晶体学信息，将该系统应用于它们。该合作研究由国际科学研究计划资助。今年在NASA/JSC选择了6种IDPs，然后在PF进行SR检测，它们是硅酸盐，硫化物和合金，直径从8到19微米。几乎所有的样品都呈现复杂的劳厄图案，显示多晶状态，具有漫射的劳厄斑点或完整的粉末线。作为晶体学研究的第一步，我们将指标赋给相对较好的样品（(Fe, Ni) S）的劳厄点，现在基于劳厄强度进行结构细化。

Interplanetary dust particles (IDPs) are considered to hold the information of an early stage of solar system. NASA/Johnson Space Center has collection of IDPs, and made preliminary investigation of them by the methods of electron prove micro analysis as well as observation through electron microscope. According to their size, X-ray diffraction method has not been applied on them. Therefore, crystallographic information are kept unknown.At the Photon Factory (PF), a system to analyze a sub micrometersized crystal has developed by using synchrotron radiation (SR) with Laue method. In order to obtain crystallographic information of IDPs, this system is applied to them. The colaborative study is performed by an aid of this International Scientific Research Program.Six IDPs were selected at NASA/JSC and then examined by SR at PF in this year are silicates, sulfides and alloys of which sizes are from eight to nineteen micrometers in diameter.Almost all samples give the complicated Laue patterns showing polycrystalline states with diffuse Laue spots or complete powder lines.As the first step of the crystallographic studies, the indices are assigned to Laue spots of the comparatively good sample ( (Fe, Ni) S) , and the structure refinement is now carried out based on Laue intensities.