Research Area 1: Advanced optical imaging and spectroscopy
Optical Nanoscopy has been pioneered in Göttingen by Stefan Hell and is under continuous development. A number of groups on Campus jointly continue to push the limits of sub-wavelength optical imaging. Among other things, current research is directed at optimum data acquisition, high scanning speed in 3D, advanced analysis by statistical modeling, creation of novel fluorescent probes and exploiting further optical control at the nanoscale.
This research area focuses on high resolution X-ray analysis in the crystalline and non-crystalline state. A particular emphasis is on soft and biological matter and in-situ probes of chemical and biological processes (Virtual Institute Helmholtz Alliance) as well as on X-ray optics and novel forms of coherent diffractive imaging (CDI) and ultra-short spectroscopy (SFB 755). It forms a bridge between the research Campus Göttingen and large scale facilities of Synchrotron- and Free-Electron-Laser-Radiation (DESY, Hamburg; European XFEL, Hamburg; LCLS, Stanford; BESSY, Berlin; Swiss Light Source, Villingen; ESRF, Grenoble).
Surfaces carry all interactions of a material with its environment, and the multi-faceted properties of a surface are governed by the complex interplay of structural, electronic and spin degrees of freedom. The Göttingen Campus combines a highly complementary set of approaches to access dynamical processes at surfaces: A powerful toolbox of state-selective surface scattering techniques using atomic and molecular beams, the first implementation of ultrafast low-energy electron diffraction (ULEED) and the ultimate temporal and momentum resolution of photoelectron spectroscopy using high-harmonic radiation uniquely combine comprehensive insights into both structural and electronic dynamics at surfaces. These approaches will be further developed to access the dynamical response of functional surfaces.
AIMS hosts a range of efforts at the forefront of electron microscopy development. Researchers in Göttingen have significantly pushed the limits in electron microscopy (EM) of biomolecular assemblies, based on sequential imaging of cryogenically fixated single particles, have lifted constraints for the sample environment (ETEM) to extend the scope of electron microscopy for materials research, and used in-situ TEM to address the central puzzles of nucleation and crack propagation in both soft and hard materials. The development of ultrafast electron microscopy (UTEM) with record temporal resolution and electron beam coherence and the implementation of tomographic methods based on focused-ion beam (FIB) microscopy to decipher 3D nanoscale structures of hard, soft and biological materials are advanced EM techniques, which are now ready to take the next challenges in 3D and 4D imaging at high resolution.
Magnetic resonance spectroscopy has a strong record and standing in Göttingen. A leading role in high resolution NMR techniques have led to a number of seminal NMR structures. In addition, kinetic and dynamic information has been exploited. EPR spectroscopy has been pushed to very high frequencies (263 GHz) and was employed to solve a variety of problems at the interface between chemistry and biophysics. Recent and planned developments across all these areas include hyperpolarization techniques for detection of nuclear spins, high power/high pressure NMR, high frequency/high power EPR. For this research area, a central impetus in joining the initiative is the synergistic implementations with other analytical techniques, such as joint structural refinements.
Fast MRI imaging has been pioneered in Göttingen, culminating in the recent advent of real-time MRI studies. While this technique is now being translated to the hospital, many challenges on a fundamental physical and mathematical level call for a continuation of research efforts. At the same time correlative approaches with other imaging methods are an important next step. Phase contrast X-ray tomography is an enabling novel imaging mode, geared at substantially higher resolution than MRI down to the micron level in tissue (propagation based) but equally capable at the organ level (grating based), and can build upon recent progress in X-ray optics and phase retrieval algorithms, as well as in specific labeling and histological preparation. Common to MRI and phase contrast X-ray tomography are the novel regularized inversion methods required to extract the information.
Development of advanced analytical techniques in imaging, microscopy, and spectroscopy is strongly supported by applied mathematics. Recent developments in mathematical statistics, information theory, and mathematics of inverse problems have opened up entirely enhanced methods to exploit and interpret experimental data. Further extending operator-independent analysis is particular necessary in view of the significant increase in experimental bandwidth, and the corresponding amount of data.
|Courant Research Centre
and X-Ray Imaging