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Gallery of the 2019 Pictures

Picture of the Month - January 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

Reversible Hydrogen Activation by a Pyridonate Borane Complex: Combining Frustrated Lewis Pair Reactivity with Boron-Ligand Cooperation

Bild des Monats Januar

 

Our group is interested in the in silico design and the synthesis of novel metal-free, molecular systems for bond activation and catalysis. One example is a pyridone borane complex that is able to activate and liberate dihydrogen under mild conditions. The hydrogen activation was followed by in-situ NMR spectroscopy, as displayed in the Figure.

This pyridone borane complex combines the reactivity of a frustrated Lewis pair (FLP) with the novel concept of boron-ligand cooperation.

This picture was submitted by Dr. Urs Gellrich.

Picture of the Month - February 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

Increased quantum efficiency of photo multiplier tubes – materials science meets Quarks and Co

Bild des Monats Februar

In the short wavelength region, the quantum efficiency (QE) of photo multiplier tubes is limited by the transparency of the window material. In order to increase this efficiency, wavelength-shifting (WLS) films consisting of organic molecules which absorb light in the UV-region but re-emit photons in the visible range of the electromagnetic spectrum were optimized in the Dürr-labs. They were then applied on multi anode photo multiplier tubes (MAPMT) which are used in the Ring Imaging Cherenkov (RICH) detectors of the HADES and CBM experiments at GSI/FAIR. Most recently, 48 of the coated MAPMTs were installed during an upgrade of the HADES detector which is now taking the first data.

The photograph (G. Otto, GSI) shows most of the 428 MAPMTs of the HADES-RICH detector with the inner 48 MAPMTs being covered by a WLS film. The increased QE is shown in the graph which we published most recently in collaboration with the CBM-/HADES-RICH groups [Adamczewski-Musch et al., Nucl. Instrum. Meth. A (2019). DOI: 10.1016/j.nima.2019.01.093].

This picture was submitted by Prof. Dr. Michael Dürr.

Picture of the Month - March 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

 

Artificial DNA-Scissors

Bild des Monats März

Compounds which alkylate and split DNA are common reagents in cancer therapy as well as antibiotics. In our group we developed an efficient synthetic approach to bis-3-chloropiperidines as such artificial DNA-alkylants. In cooperation with the groups of Barbara Gatto (pharmacy in Padova/Italy) and Daniele Fabris (mass-spectrometry in Albany) we analyse the reactivity and selectivity of these compounds.

Literature:

  • I. Zuravka, A. Sosic, B. Gatto, R. Göttlich, Synthesis and evaluation of a bis-3-chloropiperidine derivative incorporating an anthraquinone pharmacophore, Bioorg. Med. Chem.Lett. 2015, 25, 4606-4609, doi: 10.1016/j.bmcl.2015.08.042
  • A. Sosic, I. Zuravka, N.-K. Schmitt, A. Miola, R. Göttlich, D. Fabris, B. Gatto, Direct and Topoisomerase II mediated DNA damage by Bis-3-chloropiperidines: the importance of being an earnest G, ChemMedChem 2017, 12, 1471 – 1479, doi: 10.1002/cmdc.201700368
  • C. Carraro, A. Francke, A. Sosic, F. Kohl, T. Helbing, M. De Franco, D. Fabris, R. Göttlich B. Gatto, Behind the mirror: chirality tunes the reactivity and cytotoxicity of chloropiperidines as potential anticancer agents, Med.Chem.Lett. 2019, 10, doi: 10.1021/acsmedchemlett.8b00580

This picture was submitted by Tim Helbing, group of Prof. Dr. Richard Göttlich.

Picture of the Month - April 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

How One-Dimensional Are Atomic Gold Chains on a Substrate?

Bild des Monats April

One-dimensional (1D) wires are inherently unstable but can be stabilized by three-dimensional (3D) interaction with their environment, resulting in two-dimensional (2D) and 3D hybridization of 1D electronic states. The relevance of these interactions, is exemplified by the prototypical Si(553)–Au system, which forms double atomic 1D chains on each mini-terrace. The combined approach consisting of plasmon spectroscopy and first-principles calculations demonstrates the relevance of hybridization, leading to the complete breakdown of the nearly free electron gas model. Due to the coupling of the Au wires with higher dimensions through the substrate, the wires are more appropriately described as an extremely anisotropic 2D object than as purely 1D.

Publication:

This picture was submitted by Prof. Dr. Simone Sanna.

Picture of the Month - May 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

Interfacial degradation in all solid-state batteries

Bild des Monats Mai

All solid-state batteries (ASSBs) are expected to be a promising alternative to conventional lithium-ion batteries with liquid electrolytes (LIBs). In principle, high cell voltages and high specific capacities can be achieved with solid electrolytes (SE). In addition, safety aspects can be improved compared to conventional LIBs by avoiding flammable organic substances, which is particularly important in the field of electric vehicles.

However, some serious challenges still need to be overcome before this technology can be transferred to practical application. One of the key issues is the degradation of anode and cathode interfaces. This is still not fully understood and leads to an increase in cell resistance, unwanted additional overvoltage and ultimately to a strong capacity fading.

Within the “BASF International Scientific Network for Electrochemistry and Batteries” our goal is to establish the combination of time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) for the investigation of lithium-ion-based battery materials. In a recent publication, we have shown that this method combination can provide valuable insights into interfacial degradation in composite cathodes. With ToF-SIMS and XPS we were able to identify degradation products and visualize the formation of the solid electrolyte interface (SEI) layer in a LiNi0.6Co0.2Mn0.2O2/Li6PS5Cl‑composite cathode (abbreviated with NCM and SE in the figure). These results can help to optimize interfaces in composite cathodes, which is essential for the improvement of the long-term cycling stability of ASSBs. This is an important step towards the transition of this new technology to practical application.

Publications: F. Walther et al., Chem. Mater. 2019, Just Accepted Manuscript. DOI: https://doi.org/10.1021/acs.chemmater.9b00770

This picture was submitted by Felix Walther, group of Prof. Janek.

Picture of the Month - June 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

 

13. Materialforschungstag Mittelhessen am 5. Juni 2019

Bild des Monats Juni

Schon zum 13. Mal trafen sich die mit modernen Funktionsmaterialien befassten Arbeitsgruppen der drei mittelhessischen Hochschulen (Philipps-Universität, Justus-Liebig-Universität und Technische Hochschule Mittelhessen), zum Materialforschungstag Mittelhessen.
Die jährlich abwechselnd von den Universitäten Marburg und die Gießen ausgerichtete Veranstaltung fand diesmal im Hauptgebäude der JLU statt.

Nach bewährtem Muster wurde den ca. 240 Teilnehmenden ein fachlich breit gefächertes Vortragsprogramm angeboten und durch eine große Posterschau des wissenschaftlichen Nachwuchses abgerundet.

Die eingeladenen Gastredner Prof. Dr. Yan Zhang (Capital Normal University, Peking, China) und Dr. Michael Selzer (Karlsruher Institut für Technologie) berichteten über neuartige Metamaterialien zur Erzeugung von Terahertz-Wellen und über die rasant wachsenden Möglichkeiten des Hochleitungsrechnens im Design neuartiger Materialeigenschaften.

Hier finden Sie das Programm des Materialforschungstages und die Posterliste.

Foto: Dr. Martin Güngerich (ZfM/LaMa)

Picture of the Month - August 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

Test series for parameter optimization of 3D microlithography in SU-8

Bild des Monats August

Since January 2019, the Micro and Nanostructuring Laboratory has been equipped with a device for three-dimensional micro and nanolithography based on two-photon lithography (Photonics Professional GT from Nanoscribe in Eggenstein-Leopoldshafen). In two-photon lithography, a laser beam whose photon energy is not sufficient to expose a photoresist is focused by microscope optics. Around the focal point, in a volume element (voxel) which is smaller than the wavelength of the light in the lateral direction and in the vertical direction in the region of a micrometer, such a high intensity is produced that two-photon absorption takes place and the photoresist is exposed. This voxel is scanned in three dimensions by the photoresist. After processing (in the case of a "negative" resist) the exposed structure remains.

Scanning electron micrography shows a series of tests of volcanic emitters produced on a silicon substrate from the negative resist SU-8 in order to determine those parameters which represent an optimum compromise between the quality of the structure produced on the one hand and a reasonable writing time on the other. Such volcanic emitters are of interest as core components of future miniaturized electric space propulsion systems based on the electrospray effect.

The Photonics Professional GT is accessible within the MiNaLab method platform of the ZfM/LaMa, interested parties are welcome to contact at any time.

This picture was submitted by Nathalie N. Weigand (Apprentice as Microtechnologist at ZfM/LaMa).

Picture of the Month - September 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.


Potential-Induced Pitting Corrosion of IrO2(110)-RuO2(110)/Ru(0001) Model Electrodes

Bild des Monats September

Recently, sophisticated IrO2(110) ultrathin films supported on RuO2(110)/Ru(0001) were prepared and employed as model electrodes for stability studies under Oxygen Evolution Reaction (OER) conditions. In situ synchrotron-based studies (SXRD, XRR) complemented by ex situ techniques (SEM, ToF-SIMS) revealed potential-induced pitting corrosion to be operative: the degradation of the model electrode proceeds rather by disordering of the surface region than by electrochemical dissolution of the IrO2(110) film. The figure summarizes the changes in the morphology and chemical composition due to potential-induced pitting. FIB-SEM reveals a cylinder-like shape of the pits, while ToF-SIMS indicates the presence of electrochemically formed hydrous RuO2 within the pits.

This picture was submitted by Tim Weber, group of Prof. Dr. Herbert Over.

Picture of the Month - October 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

Superlubricity on the way from laboratory science to application

Bild des Monats Oktober

Superlubricity is a state of vanishing friction, where single atom energy barriers are efficiently reduced by collective interactions of larger ensembles of interface atoms. By applying lateral nanomanipulation techniques to NaCl-nanoparticles on HOPG, fundamental characteristics of this new friction state have been explored. The recent results reveal new insights into the scaling laws of superlubricity for polycrystalline interfaces. At the same time, the results hint at new strategies to transfer this technologically promising friction state from clean vacuum conditions to application under ambient conditions.

This picture was submitted by Dr. Dirk Dietzel, group of Prof. Dr. André Schirmeisen.

Picture of the Month - November 2019

Here you see current insights into the research of the LaMa groups. A collection of the former pictures can be found in the Gallery.

Experimental assessment of the practical oxidative stability of solid electrolytes

Bild des Monats November

With the growing demand in safe and abundant energy storage systems, all-solid-state batteries are often expected to replace conventional lithium-ion batteries in the future. Among the variety of solid electrolytes for lithium-based batteries, especially lithium thiophosphates stand out due to promising ionic conductivities. However, degradation reactions at the electrode interfaces represent a major bottleneck for their application. Experimentally, stabilities of thiophosphates up to 5 V vs. Li/Li+ are often claimed from cyclic voltammetry (CV) using planar working electrodes. Contradictorily, redox activity of electrolytes was observed at lower potentials in solid-state batteries. The practical electrochemical and cycling stability of lithium thiophosphates are still critical issues that prevent long-term stable high-energy cells.

Using a stepwise increase in the reversal potentials in a CV experiment in combination with a high surface area carbon-electrolyte composite working electrode, the onset potential of oxidative decomposition, i.e. the oxidation of thiophosphate building units, can be identified. Furthermore, the results suggest that the crystalline solid electrolyte itself is not redox active, but rather that only after the formation of electrolyte decomposition products, significant redox behavior is observed. Indeed, the redox behavior of the decomposition products is an additional contributor to the overall cell capacity of solid-state batteries. The method serves as an efficient guideline for the determination of practical, kinetic stability limits of solid electrolytes with respect to the employed electrode materials.

G. Dewald et alChem. Mater. 2019, DOI: 10.1021/acs.chemmater.9b01550.

This picture was submitted by Georg Dewald, group of Dr. Wolfgang Zeier.