Surface Chemistry Studies with Cluster Ion Beams

在化学系化学测量和成像项目的支持下，宾夕法尼亚州立大学的Nicholas Winograd教授和他的团队专注于阐明高能粒子与固体相互作用的基本方面，目标是推进二次离子质谱（SIMS）实验的应用。这项研究的结果将在聚合物科学、天体物理学、药物发现、有机电子学、有机光伏和分子特异性成像等不同领域找到材料表征的应用。像C60这样的簇离子源的出现为分子深度分析开辟了独特的机会。在这种情况下，分子固体的层被团簇源去除，没有明显的化学损伤积累，深度分辨率小于10纳米。这种模式提供了以前所未有的空间分辨率询问隐藏界面的可能性。分子特异性成像是SIMS的另一个独特功能，当与分子深度分析相结合时，可以产生化学的三维渲染。优化这些实验的方案将从集束轰炸事件的计算机模拟预测中发展出来，并通过在模型系统上进行实验，其中许多参数，如弹丸能量和角度，可以系统地检查。一个特别的重点放在表征气团离子束，现在产生超过2000个原子的氩团，并在寻找新的含h物质，可能通过动态创建的预形成离子增强电离。因此，最终目标是获得对团簇-固体相互作用的基本理解，并提供一种在纳米尺度上运行的基于质谱的新的三维成像协议。这种新的方法应该找到有价值的应用范围广泛的生物学家和材料科学家的表征目的。该项目将包括三名研究生的参与，他们将开发用于成像和簇离子束的新型仪器。他们将获得的技能将成为他们研究生生涯中的宝贵资产。在这项工作中，双重重点放在获得对离子-固体相互作用的基本理解，以及利用这些信息来推进应用。这一理念为项目提供了协同作用，并为参与者提供了独特的学习体验。此外，还建议通过SEECoS项目开展国际合作，并向高中生提供外展服务。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Nicholas Winograd and his group at Pennsylvania State University focus on elucidating the fundamental aspects of the interaction of energetic particles with solids, with the goal of advancing the utility of secondary ion mass spectrometry (SIMS) experiments. Results from this research should find materials characterization applications in such diverse fields as polymer science, astrophysics, drug discovery, organic electronics, organic photovoltaics and molecule-specific imaging. The emergence of cluster ion sources such as C60 has opened unique opportunities in molecular depth profiling. In this situation, the layers of a molecular solid are removed by the cluster source without significant accumulation of chemical damage and with a depth resolution of less than 10 nm. This modality offers the possibility of interrogating buried interfaces with unprecedented spatial resolution. Molecule-specific imaging is another unique feature of SIMS, and when combined with molecular depth profiling, yields a 3-dimensional rendering of the chemistry. Protocols for optimizing these experiments will be developed from predictions of computer simulations of the cluster bombardment event, and by performing experiments on model systems where a number of parameters, such as projectile energy and angle, can be systematically examined. A special emphasis is placed upon characterizing gas cluster ion beams that now produce argon clusters with more than 2000 atoms, and on searching for new H-containing species that may enhance ionization through dynamically created pre-formed ions. The ultimate goal, then, is to acquire a fundamental understanding of cluster-solid interactions and to provide a new mass spectrometry-based 3-dimensional imaging protocol that operates on the nanoscale. This new methodology should find valuable applications to a wide range of biologists and material scientists for characterization purposes. The project will include participation of three graduate students who will develop novel instrumentation for imaging and for cluster ion beams. They will acquire skills that are designed to be valuable assets in their post-graduate careers. Throughout this effort, dual emphasis is placed upon acquiring a fundamental understanding of ion-solid interactions, and of utilizing this information to advance the applications. This philosophy lends a synergism to the program and provides a unique learning experience for those involved. International collaboration and outreaching to high school students through the SEECoS program are also proposed.