Oxygen RF-Plasma Ion Source für NanoSIMS/Optical Microscope upgrade

Lehrstuhl f<e:1> r Bodenkunde， TUM， Freising正在运行一台NanoSIMS仪器，该仪器于2009年获得德国研究基金会的批准，并于2010年安装，在德国研究基金会数据库中注册，作为可对外使用的研究基础设施，重点研究土壤以及邻近的科学（地质学，微生物学，植物生理学）。使用成像和分类技术，开发用于样品制备和获得的NanoSIMS测量结果评估的特殊方法，为我们的团队和其他国内和国际用户提供了一个独特的机会，用于土壤，地质和植物材料。NanoSIMS仪器，独特的允许元素和同位素分析在纳米尺度，配备了两个离子源，铯和氧。由于不同种类的电子亲和度不同，这种结构必须覆盖广泛的测量成分。然而，在我们的研究领域，铯主要用于检测特定于有机物的离子（碳，氮），氧源需要结合起来，来描述矿物相或金属（Al, Fe,Ca， K, Mg）的定位。不幸的是，与铯相比，实际氧源的横向分辨率较差（~300nm vs ~50nm），不可预测的寿命较短（~50h），使用时间较长。这使得它的使用和性能效率较低，而且不是最优的。我们申请了一种新的射频O源，其性能得到了改善，包括对现有光学系统的升级。O-模式离子源和微束Cs+离子源之间非常相似的性能需要在有用的尺度上深入了解土壤、有机质和矿物相中主要参与者之间的相互作用。在正常工作条件下，与Cs源相比，O射频源的主光束直径为100nm，寿命长（bbb500h）， 10分钟内的稳定性优于1%，O射频源的使用增加将带来更高的输出和卓越的性能。这为我们在最佳产量和空间分辨率条件下在两种来源之间切换测量土壤相关物种（如Ca， Al, Fe）提供了更大的灵活性。

Lehrstuhl für Bodenkunde, TUM, Freising is running a NanoSIMS instrument, granted in 2009 by German Research Foundation and installed in 2010, registered on the German Research Foundation Database as a research infrastructure available for external use with focus on soil as also adjacent sciences (geology, microbiology, plant physiology). The development of special methods for sample preparation and the evaluation of the obtained NanoSIMS measurements, using imaging and classification techniques represents a unique opportunity for our group and other national and international users for soils, geologic and plant materials. The NanoSIMS instrument, uniquely allowing elemental and isotopic analyses at the nanometer scale, is equipped with two ion sources, Cesium and Oxygen. This configuration is mandatory to cover a wide spectrum of the measured constituents, due to the different electron affinity of different species. While, in our research field, Cesium is mostly used to detect ions specific for organic matter (carbon, nitrogen), the Oxygen source is needed, in combination, to depict the localization of mineral phases or metals (Al, Fe,Ca, K, Mg). Unfortunately, the actual Oxygen source has a poorer lateral resolution compared to Cesium (~300nm versus ~50nm), short unpredictable life time (~50h), yielding in long service time. This makes its usage and performance less productive and suboptimal. We apply for a new RF O source with improved performance including an upgrade for the existing optical system. Very similar performance between the ion source in O- mode and the microbeam Cs+ ion source is required to get insight in the interaction between the principal players in soil, organic matter and mineral phase at a useful scale. With a beam diameter of 100nm at usual working conditions of a 2pA primary beam comparable to the Cs source, long lifespans (>500h) and an improved stability better than 1% over 10 minutes, the increased usage of the O RF source will lead to a higher output with a superior performance. This affords us more flexibility in switching between the two sources to measure soil relevant species, such as Ca, Al, Fe at best yield and spatial resolution conditions.