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We utilize cavity-enhanced extinction spectroscopy to directly quantify the optical absorption of defects in MoS$_2$ generated by helium ion bombardment. We achieve hyperspectral imaging of specific defect patterns with a detection limit below 0.01% extinction, corresponding to a detectable defect density below $10^{11}$ cm$^{-2}$. The corresponding spectra reveal a broad sub-gap absorption, being consistent with theoretical predictions related to sulfur vacancy-bound excitons in MoS$_2$. Our results highlight cavity-enhanced extinction spectroscopy as efficient means for the detection of optical transitions in nanoscale thin films with weak absorption, applicable to a broad range of materials., Comment: 17 pages main manuscript, 7 pages supporting information

Material-selective analysis of spectral X-ray imaging data requires prior knowledge of the energy dependence of the observed signal. Contrary to conventional X-ray imaging, where the material-specific attenuation coefficient is usually precisely known, the linear diffusion coefficient of the X-ray dark-field contrast does not only depend on the material and its microstructure, but also on the setup geometry and is difficult to access. Here, we present an optimization approach to retrieve the energy dependence of the X-ray dark-field signal quantitatively on the example of closed-cell foams from projection data without the need for additional hardware to a standard grating-based X-ray dark-field imaging setup. A model for the visibility is used to determine the linear diffusion coefficient with a least-squares optimization. The comparison of the results to spectrometer measurements of the linear diffusion coefficient suggests the proposed method to provide a good estimate for the energydependent dark-field signal.

We utilize cavity-enhanced extinction spectroscopy to directly quantify the optical absorption of defects in MoS

The two-dimensional material hexagonal boron nitride (hBN) hosts luminescent centres with emission energies of 2 eV which exhibit pronounced phonon sidebands. We investigate the microscopic origin of these luminescent centres by combining ab initio calculations with non-perturbative open quantum system theory to study the emission and absorption properties of 26 defect transitions. Comparing the calculated line shapes with experiments we narrow down the microscopic origin to three carbon-based defects: $\mathrm{C_2C_B}$, $\mathrm{C_2C_N}$, and $\mathrm{V_NC_B}$. The theoretical method developed enables us to calculate so-called photoluminescence excitation (PLE) maps, which show excellent agreement with our experiments. The latter resolves higher-order phonon transitions, thereby confirming both the vibronic structure of the optical transition and the phonon-assisted excitation mechanism with a phonon energy 170 meV. We believe that the presented experiments and polaron-based method accurately describe luminescent centres in hBN and will help to identify their microscopic origin.

We demonstrate that optically active emitters can be locally generated by focusing a He-ion beam onto monolayer WS2 encapsulated in hBN. The emitters show a low-temperature photoluminescence spectrum, which is well described by an independent Boson model for localized emitters. Consistently, the photoluminescence intensity of the emitters saturates at low excitation intensities, which is distinct to the photoluminescence of excitonic transitions in the investigated WS2 monolayers. The demonstrated method allows us to position defect emitters in WS2 monolayers on demand. A statistical analysis suggests the generation yield of individual emitters to be as high as 11% at the highest investigated He-ion doses.

Atomically thin semiconductors can be readily integrated into a wide range of nanophotonic architectures for applications in quantum photonics and novel optoelectronic devices. We report the observation of nonlocal interactions of "free" trions in pristine hBN/MoS_{2}/hBN heterostructures coupled to single mode (Q10^{4}) quasi 0D nanocavities. The high excitonic and photonic quality of the interaction system stems from our integrated nanofabrication approach simultaneously with the hBN encapsulation and the maximized local cavity field amplitude within the MoS_{2} monolayer. We observe a nonmonotonic temperature dependence of the cavity-trion interaction strength, consistent with the nonlocal light-matter interactions in which the extent of the center-of-mass (c.m.) wave function is comparable to the cavity mode volume in space. Our approach can be generalized to other optically active 2D materials, opening the way toward harnessing novel light-matter interaction regimes for applications in quantum photonics.

We demonstrate that prestructured metal nanogaps can be shaped on-chip to below 10 nm by femtosecond laser ablation. We explore the plasmonic properties and the nonlinear photocurrent characteristics of the formed tunnel junctions. The photocurrent can be tuned from multiphoton absorption toward the laser-induced strong-field tunneling regime in the nanogaps. We demonstrate that a unipolar ballistic electron current is achieved by designing the plasmonic junctions to be asymmetric, which allows ultrafast electronics on the nanometer scale.

We demonstrate electrostatic switching of individual, site-selectively generated matrices of single photon emitters (SPEs) in MoS

We report magneto-photoluminescence spectroscopy of gated MoS$_2$ monolayers in high magnetic fields to 28 T. At B = 0T and electron density $n_s\sim 10^{12}cm^-2$, we observe three trion resonances that cannot be explained within a single-particle picture. Employing ab initio calculations that take into account three-particle correlation effects as well as local and non-local electron-hole exchange interaction, we identify those features as quantum superpositions of inter- and intravalley spin states. We experimentally investigate the mixed character of the trion wave function via the filling factor dependent valley Zeeman shift in positive and negative magnetic fields. Our results highlight the importance of exchange interactions for exciton physics in monolayer MoS$_2$ and provide new insights into the microscopic understanding of trion physics in 2D multi-valley semiconductors for low excess carrier densities., Comment: Main manuscript: 7 pages, 3 figures ; Supplemental material: 16 pages, 4 figures

Atomically thin semiconductors can be readily integrated into a wide range of nanophotonic architectures for applications in quantum photonics and novel optoelectronic devices. We report the observation of nonlocal interactions of \textit{free} trions in pristine hBN/MoS$_2$/hBN heterostructures coupled to single mode (Q $>10^4$) quasi 0D nanocavities. The high excitonic and photonic quality of the interaction system stems from our integrated nanofabrication approach simultaneously with the hBN encapsulation and the maximized local cavity field amplitude within the MoS$_2$ monolayer. We observe a nonmonotonic temperature dependence of the cavity-trion interaction strength, consistent with the nonlocal light-matter interactions in which the extent of the center-of-mass wavefunction is comparable to the cavity mode volume in space. Our approach can be generalized to other optically active 2D materials, opening the way towards harnessing novel light-matter interaction regimes for applications in quantum photonics.

2D materials offer a wide range of perspectives for hosting highly localized 0D states, e.g. vacancy defects, that offer great potential for integrated quantum photonic applications. Here, we create individual defects that act as our single-photon emitters by highly local He-ion irradiation in a monolayer MoS2 van der Waals heterostructure. The defects show anti-bunched light emission at a characteristic energy of ~ 1.75 eV. The emission is highly homogeneous and background free due to the hBN encapsulation with a creation yield of > 70%. Spectroscopic investigation of individual single-photon emitters reveals a strongly asymmetric line shape resembling interaction with acoustic phonons in excellent agreement with an independent boson model. Moreover, emitters are spatially integrated and electrically controlled in field-switchable van der Waals devices. Our work firmly establishes 2D materials as a highly scalable material platform for integrated quantum photonics.

We report magneto-optical spectroscopy of gated monolayer MoS$_2$ in high magnetic fields up to 28T and obtain new insights on the many-body interaction of neutral and charged excitons with the resident charges of distinct spin and valley texture. For neutral excitons at low electron doping, we observe a nonlinear valley Zeeman shift due to dipolar spin-interactions that depends sensitively on the local carrier concentration. As the Fermi energy increases to dominate over the other relevant energy scales in the system, the magneto-optical response depends on the occupation of the fully spin-polarized Landau levels in both $K/K^{\prime}$ valleys. This manifests itself in a many-body state. Our experiments demonstrate that the exciton in monolayer semiconductors is only a single particle boson close to charge neutrality. We find that away from charge neutrality it smoothly transitions into polaronic states with a distinct spin-valley flavour that is defined by the Landau level quantized spin and valley texture., Comment: Main manuscript: 7 pages, 4 figures ; Supplemental material: 20 pages, 8 figures

Trotz der unbestrittenen Bedeutung der Qualitat der Facharztweiterbildung zur Arztin/zum Arzt fur Psychiatrie und Psychotherapie existieren in Deutschland bisher keine systematischen Untersuchungen zu diesem Thema und, abgesehen von der Evaluation der praktischen Weiterbildung durch die Arztekammern, kaum Daten. In dieser Arbeit werden die Organisation der theoretischen Weiterbildung der Akademie-OWL, eines Weiterbildungsverbunds psychiatrischer Kliniken in Ostwestfalen-Lippe, und Evaluationsergebnisse dargestellt. Die Akademie-OWL fuhrt seit 2009 regelmasige Befragungen der Teilnehmer zur Qualitat der vermittelten Weiterbildungsinhalte durch. Der in Blockwochen organisierte theoretische Unterricht wird regelmasig durch die Teilnehmer mittels eines Fragebogens evaluiert, und die Ergebnisse werden an die jeweiligen Dozenten zuruckgemeldet. Diese Ergebnisse werden hier anhand eines Beispiels und in aggregierter Form als Zeitreihen anhand eines Globalbeurteilungsitems dargestellt. Sie zeigen, dass 1. die Bandbreite der Beurteilungsmoglichkeiten durch die Kandidaten genutzt wird, 2. die fachlichen Kompetenzen der Dozenten besser beurteilt werden als ihre didaktischen, 3. weder innerhalb des einzelnen Weiterbildungsverlaufs noch uber die verschiedenen Weiterbildungs-Generationen hinweg systematische Veranderungen zu beobachten sind und 4. graduelle Unterschiede der Evaluation zwischen Themengebieten und/oder Dozenten beobachtbar sind. Die Ergebnisse sprechen fur eine weitergehende systematische Untersuchung des Themas und eine systematische Forderung der didaktischen Kompetenzen der Dozenten.

Precisely positioned and scalable single-photon emitters (SPEs) are highly desirable for applications in quantum technology. This Perspective discusses single-photon-emitting atomistic defects in monolayers of MoS2 that can be generated by focused He-ion irradiation with few nanometers positioning accuracy. We present the optical properties of the emitters and the possibilities to implement them into photonic and optoelectronic devices. We showcase the advantages of the presented emitters with respect to atomistic positioning, scalability, long (microsecond) lifetime, and a homogeneous emission energy within ensembles of the emitters. Moreover, we demonstrate that the emitters are stable in energy on a timescale exceeding several weeks and that temperature cycling narrows the ensembles' emission energy distribution.

Metal-organic coordination networks self-assembled on surfaces have emerged as functional low-dimensional architectures with potential applications ranging from the fabrication of functional nanodevices to electrocatalysis. Among them, bis-pyridyl-bispyrimidine (PBP) and Fe-PBP on noble metal surfaces appear as interesting systems to reveal details of molecular self-assembly and the effect of metal incorporation on the organic network arrangement. Here, we report a combined STM, XPS, and DFT study revealing polymorphism for bis-pyridyl-bispyrimidine adsorbed adlayers on the reconstructed Au(111) surface. The polymorphic structures are converted by the addition of Fe adatoms into one unique Fe-PBP surface structure. DFT calculations show that while all PBP phases exhibit similar thermodynamic stability, metal incorporation selects the PBP structure which maximizes the number of Fe-N close contacts. Charge transfer from the Fe adatom to the Au substrate and N-Fe interactions stabilize the Fe-PBP adlayer. The increased thermodynamic stability of the metal-stabilized structure leads to its sole expression on the surface. Fil: Hötger, Diana. Max Planck Institute for Solid State Research; Alemania Fil: Carro, Pilar. Universidad de La Laguna; España Fil: Gutzler, Rico. Max Planck Institute For Solid State Research; Alemania Fil: Wurster, Benjamin. Max Planck Institute For Solid State Research; Alemania Fil: Chandrasekar, Rajadurai. Karlsruher Institut fur Technologie; Alemania Fil: Klyatskaya, Svetlana. Karlsruher Institut fur Technologie; Alemania Fil: Ruben, Mario. Karlsruher Institut fur Technologie; Alemania. Université de Strasbourg; Francia Fil: Salvarezza, Roberto Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Kern, Klaus. Max Planck Institute For Solid State Research; Alemania. École Polytechnique Fédérale de Lausanne; Suiza Fil: Grumelli, Doris Elda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina

ZnO nanoparticles have been prepared via a green electrochemical synthesis method in the presence of a polymeric anionic stabilizer (poly-sodium-4-styrenesulfonate, PSS), and then applied as inorganic component in poly-3-hexyl-thiophene thin-film transistor active layers. Different parameters (i.e. current density, electrolytic media, PSS concentration, and temperature) influencing nanoparticle synthesis have been studied. The resulting nanomaterials have been investigated by transmission electron microscopy (TEM) and spectroscopic techniques (UV-Vis, infrared, and x-ray photoelectron spectroscopies), assessing the most suitable conditions for the synthesis and thermal annealing of nanostructured ZnO. The proposed ZnO nanoparticles have been successfully coupled with a poly-3-hexyl-thiophene thin-film resulting in thin-film transistors with improved performance.

ZnO nanoparticles were prepared by a green electrochemical synthesis method applying low current densities followed by a thermal treatment. Sodium polystyrene sulphonate (PSS) was used as stabilizer in the electrolytic aqueous medium due to its biocompatibility and stability. The as-prepared nanocolloids were then annealed to improve their stability, and then converted via hydroxide species into stoichiometric oxide. Different calcination temperatures were studied. ZnO@PSS nanomaterials were deposited onto SiO2/Si substrates, in part in combination with an organic semiconductor layer to evaluate their influence on organic field effect transistors (OFETs). All nanomaterials and composite layers were characterized by morphological and spectroscopic techniques. Promising results regarding the use of ZnO@PSS in OFETs could be demonstrated.

The BARMER Ersatzkasse health fund has introduced its own procedure to make medical rehabilitation available immediately after acute care (Anschlussrehabilitation, AR). Regional cooperation among hospitals and rehabilitation clinics, a differentiated service scheme as well as extensive quality management are the main elements of this case management system. Results of the basis documentation after conclusion of the test period are presented and aspects of specific demand are discussed.

Trans-10,cis-12 conjugated linoleic acid (CLA) supplementation causes milk fat depression in dairy cows, but CLA effects on glucose metabolism are not clear. The objective of the study was to investigate glucose metabolism, especially endogenous glucose production (eGP) and glucose oxidation (GOx), as well as hepatic genes involved in endogenous glucose production in Holstein cows supplemented either with 50 g of rumen-protected CLA (9% trans-10,cis-12 and 10% cis-9,trans-11; CLA; n=10) or 50 g of control fat (24% C18:2; Ctrl; n=10) from wk 2 before parturition to wk 9 of lactation. Animal performance data were recorded and blood metabolites and hormones were taken weekly from 2 wk before to 12 wk after parturition. During wk 3 and 9 after parturition, glucose tolerance tests were performed and eGP and GOx were measured by [U-(13)C] glucose infusion. Liver biopsies were taken at the same time to measure total fat and glycogen concentrations and gene expression of pyruvate carboxylase, cytosolic phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, and carnitine palmitoyl-transferase 1. Conjugated linoleic acid feeding reduced milk fat, but increased milk lactose output; milk yield was higher starting 5 wk after parturition in CLA-fed cows than in Ctrl-fed cows. Energy balance was more negative during CLA supplementation, and plasma concentrations of glucose were higher immediately after calving in CLA-fed cows. Conjugated linoleic acid supplementation did not affect insulin release during glucose tolerance tests, but reduced eGP in wk 3, and eGP and GOx increased with time after parturition. Hepatic gene expression of cytosolic phosphoenolpyruvate carboxykinase tended to be lower in CLA-fed cows than in Ctrl-fed cows. In spite of lower eGP in CLA-fed cows, lactose output and plasma glucose concentrations were greater in CLA-fed cows than in Ctrl-fed cows. This suggests a CLA-related glucose sparing effect most likely due to lower glucose utilization for milk fat synthesis and probably because of a more efficient whole-body energy utilization in CLA-fed cows.

Electrochemical conversions at fuel cell electrodes are complex processes. Oxygen reduction and oxidation reactions (ORR and OER, respectivelly) have considerable overpotential limiting the efficiency. Effective and inexpensive catalytic interfaces are therefore essential for increased performance. Taking inspiration from enzymes, earth- abundant metal centers embedded in organic environments present remarkable catalytic active sites. We present here strategies for effectively mimicked these catalytic centers by using two- dimensional metal- organic coordination networks self- assembled on electrode surfaces. Networks consisting of an aromatic ring backbone with specific functional groups (carboxylic, pyrimidine, pyridine or cyano groups) coordinated to single Fe, Co or Cu atoms on Au(111) catalyze effectively ORR or OER and reveal distinctive catalytic activity. The results demonstrate the high potential of surface- engineered metal- organic networks for electrocatalytic conversions. Specifically designed coordination complexes at surfaces inspired by enzyme cofactors represent a new class of nanocatalysts with promising applications in electrocatalysis.

Developing efficient catalysts for electrolysis, in particular for the oxygen evolution in the anodic half cell reaction, is an important challenge in energy conversion technologies. By taking inspiration from the catalytic properties of single-atom catalysts and metallo-proteins, we exploit the potential of metal-organic networks as electrocatalysts in the oxygen evolution reaction (OER). A dramatic enhancement of the catalytic activity toward the production of oxygen by nearly 2 orders of magnitude is demonstrated for novel heterobimetallic organic catalysts compared to metallo-porphyrins. Using a supramolecular approach we deliberately place single iron and cobalt atoms in either of two different coordination environments and observe a highly nonlinear increase in the catalytic activity depending on the coordination spheres of Fe and Co. Catalysis sets in at about 300 mV overpotential with high turnover frequencies that outperform other metal-organic catalysts like the prototypical hangman porphyrins. Fil: Wurster, Benjamin. Max Planck Institute for Solid State Research; Alemania Fil: Grumelli, Doris Elda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Hötger, Diana. Max Planck Institute for Solid State Research; Alemania Fil: Gutzler, Rico. Max Planck Institute for Solid State Research; Alemania Fil: Kern, Klaus. Max Planck Institute for Solid State Research; Alemania. Ecole Polytechnique Federale de Lausanne; Suiza

To identify the microscopic origin of single-photon emitters in hexagonal boron nitride, we perform low-temperature spectroscopy. We observe strong photoluminescence at two different excitation lasers that hint at a phonon-assisted excitation scheme.