@misc{SpiekermannHarderGilmoreetal.2019, author = {Spiekermann, Georg and Harder, M. and Gilmore, Keith and Zalden, Peter and Sahle, Christoph J. and Petitgirard, Sylvain and Wilke, Max and Biedermann, Nicole and Weis, Thomas and Morgenroth, Wolfgang and Tse, John S. and Kulik, E. and Nishiyama, Norimasa and Yava{\c{s}}, Hasan and Sternemann, Christian}, title = {Persistent Octahedral Coordination in Amorphous GeO₂ Up to 100 GPa by Kβ'' X-Ray Emission Spectroscopy}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {699}, issn = {1866-8372}, doi = {10.25932/publishup-42775}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-427755}, year = {2019}, abstract = {We measure valence-to-core x-ray emission spectra of compressed crystalline GeO₂ up to 56 GPa and of amorphous GeO₂ up to 100 GPa. In a novel approach, we extract the Ge coordination number and mean Ge-O distances from the emission energy and the intensity of the Kβ'' emission line. The spectra of high-pressure polymorphs are calculated using the Bethe-Salpeter equation. Trends observed in the experimental and calculated spectra are found to match only when utilizing an octahedral model. The results reveal persistent octahedral Ge coordination with increasing distortion, similar to the compaction mechanism in the sequence of octahedrally coordinated crystalline GeO₂ high-pressure polymorphs.}, language = {en} } @article{SpiekermannHarderGilmoreetal.2019, author = {Spiekermann, Georg and Harder, M. and Gilmore, Keith and Zalden, Peter and Sahle, Christoph J. and Petitgirard, Sylvain and Wilke, Max and Biedermann, Nicole and Weis, Thomas and Morgenroth, Wolfgang and Tse, John S. and Kulik, E. and Nishiyama, Norimasa and Yava{\c{s}}, Hasan and Sternemann, Christian}, title = {Persistent Octahedral Coordination in Amorphous GeO₂ Up to 100 GPa by Kβ'' X-Ray Emission Spectroscopy}, series = {Physical Review X}, volume = {9}, journal = {Physical Review X}, number = {1}, publisher = {American Physical Society by the American Institute of Physics}, address = {Melville, NY}, issn = {2469-9926}, doi = {10.1103/PhysRevX.9.011025}, pages = {10}, year = {2019}, abstract = {We measure valence-to-core x-ray emission spectra of compressed crystalline GeO₂ up to 56 GPa and of amorphous GeO₂ up to 100 GPa. In a novel approach, we extract the Ge coordination number and mean Ge-O distances from the emission energy and the intensity of the Kβ'' emission line. The spectra of high-pressure polymorphs are calculated using the Bethe-Salpeter equation. Trends observed in the experimental and calculated spectra are found to match only when utilizing an octahedral model. The results reveal persistent octahedral Ge coordination with increasing distortion, similar to the compaction mechanism in the sequence of octahedrally coordinated crystalline GeO₂ high-pressure polymorphs.}, language = {en} } @misc{NorellJayHantschmannetal.2018, author = {Norell, Jesper and Jay, Raphael Martin and Hantschmann, Markus and Eckert, Sebastian and Guo, Meiyuan and Gaffney, Kelly J. and Wernet, Philippe and Lundberg, Marcus and F{\"o}hlisch, Alexander and Odelius, Michael}, title = {Fingerprints of electronic, spin and structural dynamics from resonant inelastic soft X-ray scattering in transient photo-chemical species}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {779}, issn = {1866-8372}, doi = {10.25932/publishup-43749}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437493}, pages = {7243 -- 7253}, year = {2018}, abstract = {We describe how inversion symmetry separation of electronic state manifolds in resonant inelastic soft X-ray scattering (RIXS) can be applied to probe excited-state dynamics with compelling selectivity. In a case study of Fe L-3-edge RIXS in the ferricyanide complex Fe(CN)(6)(3-), we demonstrate with multi-configurational restricted active space spectrum simulations how the information content of RIXS spectral fingerprints can be used to unambiguously separate species of different electronic configurations, spin multiplicities, and structures, with possible involvement in the decay dynamics of photo-excited ligand-to-metal charge-transfer. Specifically, we propose that this could be applied to confirm or reject the presence of a hitherto elusive transient Quartet species. Thus, RIXS offers a particular possibility to settle a recent controversy regarding the decay pathway, and we expect the technique to be similarly applicable in other model systems of photo-induced dynamics.}, language = {en} } @misc{McQuadeO'BrienDoerretal.2013, author = {McQuade, D. Tyler and O'Brien, Alexander G. and D{\"o}rr, Markus and Rajaratnam, Rajathees and Eisold, Ursula and Monnanda, Bopanna and Nobuta, Tomoya and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Meggers, Eric and Seeberger, Peter H.}, title = {Continuous synthesis of pyridocarbazoles and initial photophysical and bioprobe characterization}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95214}, pages = {4067 -- 4070}, year = {2013}, abstract = {Pyridocarbazoles when ligated to transition metals yield high affinity kinase inhibitors. While batch photocyclizations enable the synthesis of these heterocycles, the non-oxidative Mallory reaction only provides modest yields and difficult to purify mixtures. We demonstrate here that a flow-based Mallory cyclization provides superior results and enables observation of a clear isobestic point. The flow method allowed us to rapidly synthesize ten pyridocarbazoles and for the first time to document their interesting photophysical attributes. Preliminary characterization reveals that these molecules might be a new class of fluorescent bioprobe.}, language = {en} } @phdthesis{Justynska2005, author = {Justynska, Justyna}, title = {Towards a library of functional block copolymers : synthesis and colloidal properties}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-5907}, school = {Universit{\"a}t Potsdam}, year = {2005}, abstract = {Understanding the principles of self-organisation exhibited by block copolymers requires the combination of synthetic and physicochemical knowledge. The ability to synthesise block copolymers with desired architecture facilitates the ability to manipulate their aggregation behaviour, thus providing the key to nanotechnology. Apart from relative block volumes, the size and morphology of the produced nanostructures is controlled by the effective incompatibility between the different blocks. Since polymerisation techniques allowing for the synthesis of well-defined block copolymers are restricted to a limited number of monomers, the ability to tune the incompatibility is very limited. Nevertheless, Polymer Analogue Reactions can offer another possibility for the production of functional block copolymers by chemical modifications of well-defined polymer precursors. Therefore, by applying appropriate modification methods both volume fractions and incompatibility, can be adjusted. Moreover, copolymers with introduced functional units allow utilization of the concept of molecular recognition in the world of synthetic polymers. The present work describes a modular synthetic approach towards functional block copolymers. Radical addition of functional mercaptanes was employed for the introduction of diverse functional groups to polybutadiene-containing block copolymers. Various modifications of 1,2-polybutadiene-poly(ethylene oxide) block copolymer precursors are described in detail. Furthermore, extension of the concept to 1,2-polybutadiene-polystyrene block copolymers is demonstrated. Further investigations involved the self-organisation of the modified block copolymers. Formed aggregates in aqueous solutions of block copolymers with introduced carboxylic acid, amine and hydroxyl groups as well as fluorinated chains were characterised. Study of the aggregation behaviour allowed general conclusions to be drawn regarding the influence of the introduced groups on the self-organisation of the modified copolymers. Finally, possibilities for the formation of complexes, based on electrostatic or hydrogen-bonding interactions in mixtures of block copolymers bearing mutually interacting functional groups, were investigated.}, subject = {Blockcopolymere}, language = {en} } @article{HoangMertensWessigetal.2018, author = {Hoang, Hoa T. and Mertens, Monique and Wessig, Pablo and Sellrie, Frank and Schenk, J{\"o}rg A. and Kumke, Michael Uwe}, title = {Antibody Binding at the Liposome-Water Interface}, series = {ACS Omega}, volume = {3}, journal = {ACS Omega}, number = {12}, publisher = {American Chemical Society}, address = {Washington}, issn = {2470-1343}, doi = {10.1021/acsomega.8b03016}, pages = {18109 -- 18116}, year = {2018}, abstract = {Different signal amplification strategies to improve the detection sensitivity of immunoassays have been applied which utilize enzymatic reactions, nanomaterials, or liposomes. The latter are very attractive materials for signal amplification because liposomes can be loaded with a large amount of signaling molecules, leading to a high sensitivity. In addition, liposomes can be used as a cell-like "bioscaffold" to directly test recognition schemes aiming at cell-related processes. This study demonstrates an easy and fast approach to link the novel hydrophobic optical probe based on [1,3]dioxolo[4,5-f]-[1,3]benzodioxole (DBD dye mm239) with tunable optical properties to hydrophilic recognition elements (e.g., antibodies) using liposomes for signal amplification and as carrier of the hydrophobic dye. The fluorescence properties of mm239 (e.g., long fluorescence lifetime, large Stokes shift, high photostability, and high quantum yield), its high hydrophobicity for efficient anchoring in liposomes, and a maleimide bioreactive group were applied in a unique combination to build a concept for the coupling of antibodies or other protein markers to liposomes (coupling to membranes can be envisaged). The concept further allowed us to avoid multiple dye labeling of the antibody. Here, anti-TAMRA-antibody (DC7-Ab) was attached to the liposomes. In proof-of-concept, steady-state as well as time-resolved fluorescence measurements (e.g., fluorescence depolarization) in combination with single molecule detection (fluorescence correlation spectroscopy, FCS) were used to analyze the binding interaction between DC7-Ab and liposomes as well as the binding of the antigen rhodamine 6G (R6G) to the antibody. Here, the Forster resonance energy transfer (FRET) between mm239 and R6G was monitored. In addition to ensemble FRET data, single-molecule FRET (PIE-FRET) experiments using pulsed interleaved excitation were used to characterize in detail the binding on a single-molecule level to avoid averaging out effects.}, language = {en} } @misc{FondellEckertJayetal.2017, author = {Fondell, Mattis and Eckert, Sebastian and Jay, Raphael Martin and Weniger, Christian and Quevedo, Wilson and Niskanen, Johannes and Kennedy, Brian and Sorgenfrei, Florian and Schick, Daniel and Giangrisostomi, Erika and Ovsyannikov, Ruslan and Adamczyk, Katrin and Huse, Nils and Wernet, Philippe and Mitzner, Rolf and F{\"o}hlisch, Alexander}, title = {Time-resolved soft X-ray absorption spectroscopy in transmission mode on liquids at MHz repetition rates}, series = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam Mathematisch-Naturwissenschaftliche Reihe}, number = {780}, issn = {1866-8372}, doi = {10.25932/publishup-43752}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-437529}, pages = {12}, year = {2017}, abstract = {We present a setup combining a liquid flatjet sample delivery and a MHz laser system for time-resolved soft X-ray absorption measurements of liquid samples at the high brilliance undulator beamline UE52-SGM at Bessy II yielding unprecedented statistics in this spectral range. We demonstrate that the efficient detection of transient absorption changes in transmission mode enables the identification of photoexcited species in dilute samples. With iron(II)-trisbipyridine in aqueous solution as a benchmark system, we present absorption measurements at various edges in the soft X-ray regime. In combination with the wavelength tunability of the laser system, the set-up opens up opportunities to study the photochemistry of many systems at low concentrations, relevant to materials sciences, chemistry, and biology.}, language = {en} }