Combined TEM, NanoSIMS, Synchrotron XRF and STXM study of presolar grains and surrounding pristine matrix mineralogy with special emphasis on Acfer 094 and ALH77307

Acfer 094和ALH 77307是迄今为止发现的两颗最原始的陨石，这两颗陨石都是有据可查的。（> 160 ppm硅酸盐，> 25 ppm氧化物-Acfer 094），结合最近开发的特定场地（FIB）和大面积（阿里斯）用于TEM研究的薄膜制备技术使我们能够研究大量前太阳能硅酸盐的主要和微量元素含量以及结构特征。利用TEM、NanoSIMS、同步辐射诱导纳米XRF和STXM研究了前太阳能颗粒和周围基质矿物学。在第一个项目阶段，我们不仅开发了所需的制备和测量程序，而且已经在两个成功制备的大面积薄膜中应用NanoSIMS技术确定了9个前太阳颗粒。这些颗粒的完整化学和结构表征将是下一个重要步骤。此外，我们将把我们的工作扩展到来自原始CR族陨石的前太阳颗粒，这将由一个合作项目（见Hoppe和Zipfel的建议）确定。对太阳前硅酸盐的全面研究将使我们能够评估其母星周围的形成条件，重建冷凝-结晶过程，并确定ISM中的加工迹象，包括无定形和重结晶。我们还将研究与周围陨石基质的遗传关系。因此，我们对太阳前颗粒及其周围基质材料的多分析研究将为我们提供有关太阳系形成材料的详细信息。

It is well documented that Acfer 094 and ALH 77307 are two of the most pristine meteorites ever found. The unusual high amount of presolar grains (> 160 ppm silicates, > 25 ppm oxides - Acfer094) within the matrix mineralogy combined with the recent development of site specific (FIB) and large area (ArIS) thin film preparation techniques for TEM investigations enable us to study the main and trace element content as well as structural characteristics of a large set of presolar silicates. The presolar grains and surrounding matrix mineralogy will be studied by TEM, NanoSIMS, synchrotron induced Nano-XRF and STXM. During the first project phase we not only developed the required preparation and measurement procedure but already identified 9 presolar grains applying the NanoSIMS technique within two successfully prepared large area thin films. The complete chemical and structural characterization of these grains will be the next important step. In addition we will extend our work to presolar grains from pristine CR-clan meteorites, which will be identified by a co-operated project (see proposal by Hoppe and Zipfel). The comprehensive study of presolar silicates will enable us to assess the conditions of formation around their parent stars, to reconstruct condensation - crystallization processes and to identify signs of processing in the ISM including amorphisation and re-crystallisation. We will also study the genetic relationship with the surrounding meteorite matrix. Thus, our multi-analytical studies of presolar grains and their surrounding matrix material will give us detailed information on the material from which our solar system formed.