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

Lehrstuhl für Bodenkunde，TUM，Freising正在运行NanoSIMS仪器，该仪器于2009年获得德国研究基金会授权，并于2010年安装，在德国研究基金会数据库上注册为可供外部使用的研究基础设施，重点关注土壤以及邻近科学（地质学、微生物学、植物生理学）。使用成像和分类技术开发特殊的样品制备方法和评估所获得的NanoSIMS测量值，为我们集团和其他国家和国际土壤，地质和植物材料用户提供了独特的机会。 NanoSIMS仪器，独特地允许在纳米尺度上进行元素和同位素分析，配备了两个离子源，铯和氧。由于不同物质的电子亲和力不同，这种配置是强制性的，以覆盖广泛的测量成分。而在我们的研究领域中，铯主要用于检测有机物质（碳，氮）的特定离子，需要氧源结合起来描绘矿物相或金属（Al，Fe，Ca，K，Mg）的定位。不幸的是，与铯相比，实际的氧源具有较差的横向分辨率（~ 300 nm对~ 50 nm），不可预测的寿命短（~ 50 h），使用时间长。这使得它的使用和性能降低生产力和次优。我们申请一个新的RF O源，其性能有所改善，包括升级现有的光学系统。需要O-模式中的离子源和微束Cs+离子源之间非常相似的性能，以在有用的尺度上深入了解土壤、有机物和矿物相中的主要参与者之间的相互作用。在通常的工作条件下，2 pA初级束的束直径为100 nm，与Cs源相当，寿命长（> 500小时），并且在10分钟内稳定性优于1%，O RF源的增加使用将导致更高的输出和上级性能。这为我们在两种来源之间切换提供了更大的灵活性，以最佳产量和空间分辨率条件测量土壤相关物种，如Ca，Al，Fe。

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.