X-ray imaging at the nanoscale
Prof. T. Salditt (Institut für Röntgenphysik, Universität Göttingen)

Images of molecular functions in complex environments such as biological cells or novel composite materials are as important for the advancement of the nano and biomolecular sciences as they are difficult to obtain. They require a combination of high spatial resolution, quantitative contrast, and full compatibility with environmental conditions. Circumventing the fabrication constraints of zone plate, novel lens-less x-ray imaging techniques approaches have emerged, where the object function is reconstructed from the measured intensities without the need of an object lens.

We present recent results on x-ray imaging of test structures and biological cells [1]. In particular, we show holographic reconstructions obtained by using the quasi-point source of an x-ray waveguide to illuminate the sample [2], see Fig.1. The experimental and conceptual aspects of image formation, object reconstruction, contrast transfer function and resolution of imaging with a quasi point-source imaging will be discussed. Examples of phase contrast projection imaging and x-ray fluorescence imaging of membranes and biological cells will be presented.

[1] K. Giewekemeyer,et al.?Quantitative biological imaging by ptychographic x-ray diffraction microscopy?, PNAS 107 (2), 529 (2010)

[2] K. Giewekemeyer,et al.?Holographic and diffractive x-ray imaging using waveguides as quasi-point sources?, New Journal of Physics (2010); S. Kalbfleisch et al., AIP Conf. Series, in press; Giewekemeyer et al, Physical Review (2011),