Interdisciplinary Instrumentation Colloquium
David Shapiro, "X-ray Ptychography at the Advanced Light Source: a bright tool for nano-science"
Wednesday, 30 August 2017 from to (US/Pacific)
The limitations of x-ray optics are understood and analogous to the limitations faced by electron microscopy decades ago. Advances in electron imaging systems, primarily through correction of aberrations, have enabled sub-Å spatial resolution and revolutionized our ability to study the nano-scale world. A similar revolution is under way in the field of x-ray microscopy as we develop the experimental, theoretical and computational means of producing a complete description of coherent imaging systems from diffraction data. These methods not only allow for full quantification and removal of all optical aberrations but also extension of the numerical aperture to the wavelength limit. One such method under intensive development by researchers around the world is x-ray ptychography. This is a scanned probe method that reconstructs a scattering object and its illumination from coherent diffraction data. Within the first few years of development at the Advanced Light Source (ALS), Lawrence Berkeley National Laboratory, this method has already achieved the highest resolution x-ray images ever recorded in two, three and four dimensions. With the ability of x-rays to penetrate significantly more matter than electrons, their short wavelength and their sensitivity to chemical and magnetic states, there is potential for x-ray ptychography to revolutionize how we see nano-scale materials. In this presentation I will briefly describe the technical framework for how various diffractive imaging methods work and will give a detailed account of a practical implementation at the ALS with several scientific applications ranging from ion intercalation in battery materials to hydration reactions in cement. The ALS has a new facility for coherent imaging, called COSMIC, which aims to provide single-nanometer spatial resolution x-ray microscopy for materials science. X-ray beamline commissioning is currently underway and I will present the radically new microscope design required to meet the goals of this new facility.