VH-VI-203
Nano-Scale Imaging Using Coherent Hard X-rays
Programmorientierte Förderung von DESY
Nano-Scale Imaging Using Coherent Hard X-rays
Deutsches Elektronen-Synchrotron DESY
Notkestr. 85
22607 Hamburg
Georg-August-Universität Göttingen
Institut für Röntgenphysik
Friedrich-Hund-Platz 1
D-37077 Göttingen
Technische Universität Dresden
Institut für Strukturphysik
Zellescher Weg 16
D-01062 Dresden
In view of the growing demand for imaging tools in nano- and bio-sciences, the established microscopy and spectroscopy techniques are facing strong limitations, with regard to spatial resolution, sample volume, sample environment, penetrative power, scanning time or chemical sensitivity. In contrast to electron microscopy and scanning microscopy techniques, X-ray imaging has the potential of inspecting samples not only on the surface, but also in the bulk (for example entire biological cells) and in aqueous environment, without the need for cutting, fixing or drying the sample. At the same time short wavelengths enable the necessary resolution to observe molecular structure and dynamics. However, all direct X-ray imaging techniques (using optics), both in the soft and hard X-ray regime, are currently limited in spatial resolution to a couple of ten nanometers. Far field diffraction imaging (lensless imaging) with coherent illumination allows one at least in principle to overcome this resolution limit by reconstructing the electron density of the object from the far field diffraction pattern using phase retrieval techniques (oversampling).
The two future X-ray sources at DESY, PETRA III and the European-XFEL, will both have complementary but unsurpassed beam properties making them particularly suited for microscopic studies. Their high brilliance and high degree of spatial coherence are ideally suited for the implementation of coherent X-ray diffraction imaging methods that are currently being developed.
It is the aim of this virtual institute to develop further experimentally and theoretically far field diffraction imaging (lens less imaging) and tomographic techniques based thereon to potentially overcome the resolution limit of other direct X-ray microscopy techniques and obtain three-dimensional structural information from bulk samples at high spatial resolution.
We would like to investigate the potential and limitations of the technique, taking for example partial coherence, photon statistics, and radiation damage into account. Besides experimental issues, lens less imaging requires sophisticated modeling and the development of phase retrieval algorithms. Further developments are the combination with scanning and inline holographic techniques. The properties of X-ray optics, i.e., waveguides and refractive lenses, will be investigated in view of their applicability to coherent diffraction imaging, in particular to focusing the primary beam onto the sample while preserving the wave field properties.
Samples to be studied will range from nano structured phantoms for systematic technique developments and nano structured surfaces and semi-conductor devices to small biological samples like whole cells.
Ansprechpartner bei DESY:
Deutsches Elektronen-Synchrotron
Hamburger Synchrotronstrahlungslabor
Prof. Dr. Edgar Weckert
Notkestr. 85
D-22607 Hamburg
e-mail: edgar.weckert@desy.de
Tel.: 040 8998 4509
Fax: 040 8998 4475
Ansprechpartner bei der Georg-August-Universität Göttingen:
Prof. Dr. Tim Salditt
Institut für Röntgenphysik
Friedrich-Hund-Platz 1
D-37077 Göttingen
e-mail: tsaldit@gwdg.de
Tel.: 0551 399427
Fax: 0551 399430
Ansprechpartner bei der Technischen Universität Dresden:
Prof. Dr. Christian Schroer
Institut für Strukturphysik
Zellescher Weg 16
D-01062 Dresden
e-mail: schroer@physik.tu-dresden.de
Tel.: 0351 463 37589
Fax: 0351 463 37048
