Advancing Soft X-ray Spectromicroscopy

我的团队为内壳层激发光谱仪和光谱显微镜开发新的仪器、技术和应用。我们使用这些方法来研究广泛的化学、环境、能源科学和纳米材料系统。我们的强项是发展对内壳激发光谱如何取决于材料的化学结构和物理性质的基本理解，然后利用这一知识分析具有技术和社会意义的材料和工艺。我们的研究范围从小分子类似物的实验和计算研究(例如，作为燃料电池膜中质子传输磺酸盐位置的类似物)，到探索软X射线光谱显微镜的新的和具有挑战性的应用，这往往需要开发新的检测方案和现场方法。在过去的5年里，扫描透射式X射线显微镜(STXM)已经成为我们主要的研究工具。在接下来的五年里，我们将进一步扩大加拿大光源(CLS，萨斯卡通)和高级光源(ALS，伯克利)的X射线光谱显微镜仪器和技术，并将新仪器用于广泛的科学领域。在CLS，我们正在建造一种全新的STXM，致力于使用冷冻光谱层析和冷冻光谱层析技术测量定量的3D化学分布。层析成像是一种革命性的X射线成像新方法，通过在样品上的重叠点阵列测量相干衍射图案，然后使用先进的相位检索方法创建图像，大大提高了空间分辨率。最近用软X射线光刻技术获得了1.5 nm的空间分辨率。相比之下，STXM的分辨率通常为30 nm，最多为15 nm，配备最先进的光学技术。新的CRYO-STXM将被用于在汽车应用的背景下帮助改进燃料电池材料及其制造工艺，并用于研究趋磁细菌等生物系统。我们还将对金属沉积过程(与半导体器件工艺相关)进行原位流体流动和电化学研究，并使用原位流动和电位偏差来可视化与理解阳离子抗菌肽抗菌活性机制相关的肽-脂相互作用。在肌萎缩侧索硬化症研究所，我们正在开发燃料电池和趋磁细菌样本的光谱分析应用。

My group develops novel instrumentation, techniques and applications for inner-shell excitation spectroscopies and spectromicroscopies. We use these methods to study a wide range of chemical, environmental, energy sciences, and nanomaterials systems. Our forte is developing a fundamental understanding of how inner shell excitation spectra depend on the chemical structure and physical properties of a material, and then to use that knowledge for analysis of materials and processes of technological and societal importance. Our research ranges from experimental and computational studies of small molecule analogs (e.g. CF3SO3H as an analog to the proton transport sulfonate site in fuel cell membranes), to exploring novel and challenging applications of soft X-ray spectromicroscopies, which often require the development of new detection schemes and in situ methods. Over the past 5 years, scanning transmission X-ray microscopy (STXM) has become our major research tool. In the next five years, we will further expand X-ray spectromicroscopy instrumentation and techniques at the Canadian Light Source (CLS, Saskatoon) and the Advanced Light Source (ALS, Berkeley) and exploit the new instrumentation for a wide range of science. At CLS we are building a radically new STXM dedicated to measuring quantitative 3D chemical distributions using cryo-spectro-tomography and cryo-spectro-ptychography. Ptychography is a revolutionary new approach to X-ray imaging which greatly improves spatial resolution by measuring coherent diffraction patterns at an array of overlapping points on the sample and then creating the image using advanced phase retrieval methods. A spatial resolutions of 1.5 nm was recently  achieved with soft X-ray ptychography. In contrast, STXM resolution is routinely 30 nm and at best, 15 nm with state-of-the-art optics. The new cryo-STXM will be used to help improve fuel cell materials and their manufacturing processes in the context of automotive applications, and to investigate biological systems such as magnetotactic bacteria. We will also perform in situ fluid flow and electrochemical studies of metal deposition processes (relevant to semiconductor device processes), and use in situ flow and potential bias to visualize peptide - lipid interactions relevant to understanding mechanisms of antimicrobial activity of cationic antimicrobial peptides. At the ALS we are developing applications of spectro-ptychography to fuel cell and magnetotactic bacteria samples.