Forschungszentrum
Forschungsprojekte

Forschungsprojekte

  • On the interaction of guest molecules with Co-MOF-74: A Vis/NIR and Raman approach
    We were able to demonstrate the strongly anisotropic absorption behavior of Co-MOF-74 rod like crystals with a length of several hundred micrometers illuminated by polarized light. Afterwards Co-MOF-74 has been evaluated for selective gas sensing. Several gases (CO2, propene, propane, Ar, MeOH, H2O) can be detected and distinguished by Co-MOF-74 due to their interactions with the Co2+- centers.
    Leitung: Dorfs & Caro
    Jahr: 2018
  • Prozesstechnik und Modellierung der Synthese maßgeschneiderter ZrO2-Nanopartikel
    Nanostrukturiertes Zirconium(IV)-Oxid ist aufgrund seiner hohen chemischen und thermischen Stabilität, seiner geringen Toxizität und seiner vorteilhaften mechanischen Eigenschaften von großem Interesse für verschiedenste Anwendungen auf den Gebieten der technischen Keramik, für Katalysatoren oder Elektronikkomponenten. Jedoch ist seine Performance maß-geblich von den spezifischen Eigenschaften der zugrunde liegenden Nanopartikel abhängig. Insbesondere deren Partikelgröße und Kristallitgröße, Morphologie oder Phasenzusammensetzung sind von großer Bedeutung und müssen somit genau kontrolliert werden.
    Leitung: Bigall & Garnweitner
    Jahr: 2018
  • Development of 3D human cells-based microvessels microfluidic model for replacement of ani-mals in microvascular disease study
    It has been recognized that microcirculation plays an important role in pathogenesis of many diseases. Understand-ing and regulation of microvasculature are urgently needed for developing effective therapeutic strategies. Howev-er, suitable models allowing in depth biomedical research of microcirculation are missing. Most of the research is performed with the use of animal models. The main aim of the project is to develop human cells-based microvessel microfluidic model (HZ-MMM). Vessels are grown from microvascular endothelial cells (EC) and accompanying cells in a microfluidic device by the process of angiogenesis. The model is adjusted for applications in basic research and drug development.
    Leitung: Chichkov
    Jahr: 2017
  • Improved hydrogen selectivity of Surface Modified Graphite (SMG) membranes: Permeation experiments and characterisation by micro-Raman spectroscopy and XPS
    Graphit ist ein preiswertes 2D-Kohlenstoffmaterial, dessen Flocken sich durch uniaxiales Pressen relativ leicht zu etwa 1mm dicken Scheiben verformen lassen. Diese verpressten Graphitscheiben wurden als gastrennende Membran evaluiert. Bereits ohne jegliche Oberflächenbehandlung ergaben sich überraschend hohe Trennfaktoren in der Abtrennung von Wasserstoff aus den Gemischen mit Kohlendioxid und Wasserdampf. Im Projekt zeigen wir, dass durch Oberflächensilanierung dieser Trenneffekt weiter gesteigert werden kann . Durch Zusammenarbeit im LNQE konnte durch XPS und Micro-Raman der molekulare Mechanismus der Wechselwirkung aufgeklärt und verstanden, und dadurch letztlich optimiert werden. Die oberflächenmodifizierten Graphite werden „surface modified graphite“ (SMG) genannt.
    Leitung: Tegenkamp & Caro
    Jahr: 2017
  • Spin and reoccupation noise beyond the fluctuation-dissipation theorem
    we have measured the non-equilibrium spin noise of a homogeneously broadened single quantum dots in a microcavity. The measurements in combination with a theoretical analysis beyond the fluctuation-dissipation theorem reveal the spin dynamics in the ground and the excited state of the strongly driven artificial atom which is potentially useful for spin-photon interfacing.
    Leitung: Oestreich
    Jahr: 2017
  • Graphene ähnliche und leitfähige 2D Metallorganische Gerüstverbindungen als Nanosensoren
    In den letzten Jahren haben sich die metallorganischen Gerüstverbindungen (engl.: metal-organic frameworks, MOFs) zu einem sehr großen Forschungsbereich entwickelt. Besonders die zum Teil extrem hohen spezifischen Oberflächen in Kom-bination mit der Möglichkeit zur chemischen Modifizierbarkeit des gesamten Materials machen diese Materialklasse attraktiv für verschiedene Anwendungsgebiete, da die MOFs auf die gewünschte Fragestellung angepasst werden können. Vorversuche haben gezeigt, dass es möglich ist sehr sensitive Oberflächen zu erhalten, die schnell auf Testgase wie Kohlenstoffdioxid sowie Methanol in einem Trägergasstrom reagieren. In diesem Teilprojekt ist vor allem von Interesse diese Materialien auf Interdigitalelektroden aufzubringen und quantitative Messungen mit verschiedenen Analytkonzentrationen durchzuführen, sodass diese Materialien in Sensoren eingesetzt werden können.
    Leitung: Haug, Zimmermann & Behrens
    Jahr: 2017
  • Lokalisierte Oberflächenplasmonenresonanz verschiedener Nickelsulfid Nanostrukturen
    Es konnten erfolgreich plasmonische Nanostrukturen aus zwei unterschiedlichen Nickelsulfid-Phasen hergestellt werden, welche lokalisierte Oberflächenplasmonenresonanzen im sichtbaren Bereich des elektromagnetischen Spektrums aufweisen. Damit konnte das Forschungsgebiet der Materialien mit Resonanzfrequenzen in diesem Bereich, welches bisher vornehmlich von Edelmetallpartikeln dominiert wurde, durch deutlich kostengünstigere Materialien erweitert werden.
    Leitung: Dorfs
    Jahr: 2017
  • Gold-Aerogele zur Detektion von elementarem Quecksilber in der Gasphase
    Quecksilber wird in großen Mengen durch industrielle Prozesse freigesetzt. Da Quecksilber sehr toxisch ist, werden zum Schutz des Menschen Sensoren benötigt, welche in der Lage sind, geringe Quecksilberkonzentrationen zu detektieren. Der Quecksilbersensor in diesem Projekt besteht aus zwei Kupferelektroden auf einer Leiterplatte, zwischen denen in einem Spalt ein Gold-Aerogel aufgebracht ist. Der Sensor nutzt die Bildung eines Amalgams beim Kontakt von Quecksilber mit Gold als Messeffekt aus und detektieren eine Masse- bzw. Widerstandsänderung.
    Leitung: Bigall & Zimmermann
    Jahr: 2017
  • Azobenzene Guest Molecules as Light-Switchable CO2 Valves in an Ultrathin UiO-67 Membrane
    an UiO-67 membrane was prepared and characterized for the first time in terms of its H2 purification properties. Further, a light switchable guest molecule was introduced into the MOF network, which could be used to switch the gas transport of CO2 by light over the permeance of H2, resulting in selectivity changes. Thereby, an easy and cheap way of making a switchable membrane was achieved and functionally tested.
    Leitung: Behrens & Caro
    Jahr: 2017
  • Optionen zur Realisierung von Si-Solarzellen mit Effizienzen über 26%
    Der Wirkungsgrad von Solarzellen wird, angesichts des immer größer werdenden Anteils der BOS (balance of system)-Kosten an einem PV-System, zum entscheidenden Faktor für eine weitere Reduktion der PV-Stromgestehungskosten. In dem „26+“-Projekt sollen „Leuchtturmeffizienzen“ von über 26% erreicht werden. Wir verfolgen den Ansatz, passivierende Kontakte aus polykristallinem Silizium auf Oxid (POLO) anstatt amorphes Silizium zu verwenden, da die POLO-Kontakte temperaturstabiler und somit mit einer konventionellen Siedruckmetallisierung vereinbar sind.
    Leitung: Brendel & Osten
    Jahr: 2016
  • Strong suppression of shot noise in a feedback controlled single-electron transistor
    We demonstrate the strong suppression of shot noise in a single-electron transistor using an exclusively electronic closed-loop feedback. The occurrence of shot-noise, due to the random emission of electrons with the quantized charge e-, was first postulated in vacuum diodes by W. Schottky in 1918 and is becoming the dominant source of noise in present-day mesoscopic conductors. Our technique is analog to the generation of squeezed light in quantum optics, using in-loop photo detection.
    Leitung: Haug
    Jahr: 2016
  • Plasmonic Semiconductor Nanoparticles in a Metal-Organic Framework Structure and their In Situ Cation Exchange
    In this work we present the successful integration of two plasmonic semiconductor systems into the nanoporous MOF type ZIF 8. Both systems are potentially interesting for sensory application in which the ZIF network is size discriminating the access to the LSPR particles and can be either used for optical sensing of redox active substances or for simply sensing changes in the dielectric surrounding.
    Leitung: Caro & Dorfs
    Jahr: 2016
  • Amorphous, turbostratic and crystalline carbon membranes with hydrogen selectivity
    Hydrogen production by catalytic steam reforming of renewable hydrocarbons like bio-methane or bio-ethanol has become an attractive goal of sustainable chemistry. Side reactions as in ethanol steam re-forming decrease the hydrogen selectivity. A low-temperature catalytic membrane reactor with a hydrogen-selective membrane is expected to solve this problem. Three different carbon membranes are investigated with respect to their performance to extract hydrogen selectively.
    Leitung: Tegenkamp & Caro
    Jahr: 2016
  • Self-Assembly of CdSe and CdSe/CdS Nanoplatelets to Form Highly Porous Fluorescent Aerogels
    A synthetic strategy to obtain highly porous aerogels from quasi 2D 5 ML thick CdSe and CdSe/CdS NPLs is presented. The aerogels partially exhibit the quantum confinement properties of their initial building blocks with a highest absolute quantum yield of 10.3%. The aerogels solely exhibit (111) as the exposed crystal facet. This type of extremely lightweight aerogels with high porosities and BET specific surface areas are promising for future applications for e.g., facet dependent catalytic reactions or in sensing chemicals.
    Leitung: Behrens & Bigall
    Jahr: 2016
  • Versatile fabrication method for aerogels by freezing and subsequent freeze-drying of colloidal nanoparticle solutions
    We present a novel approach for synthesizing aerogels by shock-freezing colloidal nanoparticle in liquid nitrogen and subse-quent freeze drying. With this simple method it is possible to assemble nanoparticle into macroscopic voluminous monoliths, while retaining most of their properties such as size, shape or optical properties. In comparison to state of the art techniques it is a lot faster and easier to handle. This procedure might bridge the gap for scaled-up production and might enable industrial applications.
    Leitung: Bahnemann & Behrens & Bigall
    Jahr: 2016
  • Aerogels from CdSe/CdS Nanorods with Ultra-long Exciton Lifetimes and High Fluorescence Quantum Yields
    Hydrogels and aerogels from CdSe/CdS nanorods have been fabricated. By precisely controlling the gelation process, gels with high photoluminescence quantum yield and ultra-long exciton lifetime can be obtained. Thus, this type of assemblies represents a very promising way to fabricate materials that present new or improved characteristics with respect to both the colloidal solution and the bulk.
    Leitung: Dorfs & Bigall
    Jahr: 2015
  • Raman spectroscopy and tunneling microscopy on epitaxially grown graphene nanoribbons
    We have characterized in this joint collaboration Graphene nanoribbons, grown selectively on the sidewalls of SiC mesa. The identification of charge neutrality, monolayer thickness as well as the zig-zag orientation is important and a prerequsiste for the ballisitic transport behavior.
    Leitung: Oestreich & Tegenkamp
    Jahr: 2015
  • Oxidations of Alcohols under Inductively-Heated Flow Conditions with Gold-Doped Superparamagnetic Nanoparticles as Catalyst and Oxygen as Oxidant
    A continuous flow protocol for the oxidation of alcohols to aldehydes and ketones, respectively, using oxygen gas or atmospheric air is reported. The key features of this work are gold nanoparticles that are attached to the surface of nanostructured core shell particles composed of an Fe3O4-containing core and a silica shell. These nanostructured particles exert superparamagnetic properties and thus inductively heat up in an external oscillating electromagnetic field, conditions under which the gold cata-lyst is able to perform these oxidation reactions.
    Leitung: Kirschning
    Jahr: 2015
  • Microfabricated atom traps for quantum information science and precision measurements
    Microfabrication holds great promise for a new class of atomic and molecular quantum systems based on scalable and compact trapping structures. These systems have found applications both in quantum information science, novel types of quantum sensors and precision experiments. We design, fabricate, characterize and operate microfabricated neutral atom and ion chip-scale traps both at LNQE and in the PTB cleanroom facility.
    Leitung: Ospelkaus & Rasel
    Jahr: 2015
  • Site-Selective Noble Metal Growth on CdSe Nanoplatelets
    In this work, we have grown Au, Pd, and Pt metal domains site-selectively on quasi 2D CdSe nanoplatelets of 5 monolayer thickness. Au and Pd domains are found mainly at the corner and at the shorter edges of the NPLs, whereas the Pt domains are all around the edges of the nanoplatelets. The different morphologies obtained for different metals are attributed to the type of metal precursor and to the varied reaction parameters.
    Leitung: Bigall
    Jahr: 2015
  • Superlattice Structures in Twisted Bilayers of Folded Graphene
    The electronic properties of bilayer graphene strongly depend on relative orientation of the two atomic lattices. Whereas Bernal-stacked graphene is most commonly studied, a rotational mismatch between layers opens up a whole new field of rich physics, especially at small interlayer twist. We investigate magnetotransport measurements on twisted graphene bilayers, prepared by folding of single layers. These reveal a strong dependence on the twist angle, which can be estimated by means of sample geometry.
    Leitung: Haug
    Jahr: 2014
  • Micro- and Mesoporous Silica and Titania for Catalysis, Biomedizin, Photonics
    The results presented here show novel possibilities to combine the laser-based top-down approach of structuring materials on the micrometer scale by two-photon polymerization (2PP) technique with a chemical bottom-up self-organization process for producing artificial hierarchically ordered porous media for applications in chemistry, biomedicine, and photonics.
    Leitung: Chichkov & Behrens
    Jahr: 2014
  • Oxidations of Allylic and Benzylic Alcohols under Inductively-Heated Flow Conditions with Gold-Doped Superparamagnetic Nanostructured Particles as Catalyst and Oxygen as Oxidant
    A continuous flow protocol for the oxidation of alcohols to aldehydes and ketones, respectively, using oxygen gas or atmospheric air is reported. The key features of this work are gold nanoparticles that are attached to the surface of nanostructured core shell particles composed of an Fe3O4-containing core and a silica shell. These nanostructured particles exert superparamagnetic properties and thus inductively heat up in an external oscillating electromagnetic field, conditions under which the gold catalyst is able to perform these oxidation reactions.
    Leitung: Kirschning
    Jahr: 2014