Advancing Soft X-ray Spectromicroscopy

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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.