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Item Zeitschriftenaufsatz Open Access Tests als Medien der Gewöhnung : Pilotversuche am Bahnhof(2023) Schabacher, Gabriele; Spallinger, SophieItem Zeitschriftenaufsatz Open Access Data papers : an introduction(2023) Schneider, Alexandra; Hagener, MalteIn order to diversify the scope of scholarly formats within NECSUS, the new section Data Papers offers a curated platform for publishing commented datasets from film and media studies research projects. It invites researchers to share insights into the often invisible collaborative work of data preparation and dataset collection.Item Zeitschriftenaufsatz Open Access Suppressing non-radiative relaxation in a NIR single photon emitter : the impact of deuteration and temperature(2024) Mishra, Krishna; Wu, Zehua; Erker, Christian; Müllen, Klaus; Basché, ThomasThe fluorescence quantum yield of organic NIR-emitters is typically limited by internal conversion (IC), restricting their applications in imaging and quantum technology. Here, we study the impact of deuteration and temperature on the emission properties of dibenzoterrylene (DBT) by bulk and single molecule spectroscopy. Based on simple photophysical modelling, we first clarify how IC affects the single molecule emission rate. Next, we show that deuteration of DBT leads to a concomitant increase in the fluorescence lifetime and quantum yield by up to 60%. This clear deuterium isotope effect indicates a significant contribution of C–H-vibrations in the IC process. The solvent-dependent changes in the IC rate of hydrogenated and deuterated compounds were found to follow the predictions of the energy gap law in the weak coupling limit. This view is supported by the very weak temperature dependence of the IC rate between 5 and 300 K. Our results not only shed light on the non-radiative relaxation of a topical polItem Zeitschriftenaufsatz Open Access Bridge editing of spin-flip emitters gives insight into excited state energies and dynamics(2024) Reichenauer, Florian; Naumann, Robert; Förster, Christoph; Kitzmann, Winald R.; Reponen, Antti-Pekka M.; Feldmann, Sascha; Heinze, KatjaSix-coordinate chromium(III) complexes with high spin-flip (SF) photoluminescence quantum yields and lifetimes (molecular rubies) have attracted huge interest in the past years due to their applicability in sensing, photocatalysis or circularly polarised emission. However, clearcut design rules for high quantum yields and lifetimes are still lacking due to the multidimensional problem of the non-radiative decay of the SF states. Based on an isostructural series of complexes differing in the ligand backbone, we disentangle decisive structural and electronic features for SF excited state energies and non-radiative decays promoted by spin–orbit coupling, Jahn–Teller distortions and (thermally activated) multiphonon relaxation. This analysis goes beyond the classical increasing of the ligand field strength or the metal–ligand covalency to reduce non-radiative decay or to tune the SF energy. The results underscore the utility of the combination of near-infrared absorption, variable temperature emission and fs-transient absorption spectroscopy as well as photolysis and high-level quantum chemical calculations to obtain a comprehensive picture of the excited dynamics on ultrafast and long timescales.Item Zeitschriftenaufsatz Open Access Kanon(2024) Zilch, Leonie; Linseisen, Elisa; Horn, SarahItem Zeitschriftenaufsatz Open Access Ring opening of photogenerated azetidinols as a strategy for the synthesis of aminodioxolanes(2024) Maag, Henning; Lemcke, Daniel J.; Wahl, Johannes M.α-Aminoacetophenones are identified as promising building blocks for the synthesis of highly substituted dioxolanes. The presented strategy is founded on the build and release of molecular strain and achieves a formal transposition of a methyl group. During light irradiation, 3-phenylazetidinols are forged as reaction intermediates, which readily undergo ring opening upon the addition of electron-deficient ketones or boronic acids. Key to the successful development of this two-step process is the identification of a benzhydryl-protecting group, which orchestrates the photochemical Norrish–Yang cyclization and facilitates the subsequent ring opening.Item Zeitschriftenaufsatz Open Access Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis(2024) Rocker, Johannes; Zähringer, Till J. B.; Schmitz, Matthias; Opatz, Till; Kerzig, ChristophOrganic photocatalysts frequently possess dual singlet and triplet photoreactivity and a thorough photochemical characterization is essential for efficient light-driven applications. In this article, the mode of action of a polyazahelicene catalyst (Aza-H) was investigated using laser flash photolysis (LFP). The study revealed that the chromophore can function as a singlet-state photoredox catalyst in the sulfonylation/arylation of styrenes and as a triplet sensitizer in energy transfer catalysis. The singlet lifetime is sufficiently long to exploit the exceptional excited state reduction potential for the activation of 4-cyanopyridine. Photoinduced electron transfer generating the radical cation was directly observed confirming the previously proposed mechanism of a three-component reaction. Several steps of the photoredox cycle were investigated separately, providing deep insights into the complex mechanism. The triplet-excited Aza-H, which was studied with quantitative LFP, is formed with a quantum yield of 0.34. The pronounced triplet formation was exploited for the isomerization reaction of (E)-stilbene to the Z-isomer and the cyclization of cinnamyl chloride. Catalyst degradation mainly occurs through the long-lived Aza-H triplet (28 µs), but the photostability is greatly increased when the triplet efficiently reacts in a catalytic cycle such that turnover numbers exceeding 4400 are achievable with this organocatalyst.Item Zeitschriftenaufsatz Open Access NMRium : teaching nuclear magnetic resonance spectra interpretation in an online platform(2024) Patiny, Luc; Musallam, Hamed; Bolaños, Alejandro; Zasso, Michaël; Wist, Julien; Karayilan, Metin; Ziegler, Eva; Liermann, Johannes C.; Schlörer, Nils E.NMRium is the first web-based software that allows displaying, processing, interpretation, and teaching of 1D and 2D NMR data in a user-friendly interface. It can import the most common data formats (e.g., JCAMP-DX, Bruker, Varian, and Jeol). While the scope for the use of NMRium encompasses a variety of applications such as being a component in data repositories or electronic lab notebooks (ELN), performing structure elucidation or preparing raw spectral data for publication, it also excels in enhancing teaching of NMR interpretation. In this paper, we present some current possibilities of this new tool. Several series of exercises are already provided on https://www.nmrium.org/teaching.Item Zeitschriftenaufsatz Open Access A digital trail of rupture : the German film exile 1933-1945 in the data of Günter Peter Straschek(2024) Klages, ImmeHow can digital humanities methods reveal the productivity and connectedness of a group of historical individuals linked by displacement from a country? German film exile during National Socialism, 1933-1945, has always been a complex subject to research because of the scattered nature of the sources in the international distribution of archives (Asper, Horak, Hilchenbach). It remains challenging to reconstruct the worldwide dispersed separate flight routes of more than 3000 individuals who worked for the German film industry before 1933. This contribution concerns a list of film exiles collected by the exile researcher and filmmaker Günter Peter Straschek (1942-2009), whose collection of files belongs to the German National Library, German Exile Archive 1933-1945, Frankfurt am Main and was inventoried according to their Normdata. To this end, a database of GND exile data containing names, birth and death dates, professions, and countries of exile was compiled and enriched with data from online resources (Wikidata and IMDb). How can a more comprehensive look at the data reveal the devastating loss for German film (2) and, on the other hand, the collaboration on the flight (3) showing exiles remaining defiant? By incorporating new data from the Straschek Estate, digital methods further enhance historical research findings.Item Zeitschriftenaufsatz Open Access Clause-Initial Connectives, bound and unbound : indicators of mood, of subordination, or of something more fundamental?(2023) Wiemer, BjörnThe article presents a comprehensive discussion of distinctions which, in different linguistic traditions, are associated with the concepts of ‘mood’ and ‘complementizer’, in particular in connection with potential auxiliaries of ‘analytical (non-indicative) mood’. On the basis of a selection of representative units and clause frames, the analysis points out contrasts between (a) North and South (in particular, Balkan) Slavic and (b) volition- and cognition-oriented utterances, which distinguish (i) diverse kinds of illocutions and (ii) clauses coding states of affairs (i.e. mere events) vs propositions (i.e. events with specific anchorage in space and time). The discussion unavoidably raises issues of irrealis marking and asks for the diagnostics of ‘subordination’ (embedding), in particular whether left-edge elements can by themselves be regarded as complementizers even if, under specific circumstances, subordination has to be assumed.Item Zeitschriftenaufsatz Open Access Polish jakoby : an exotic similative-reportive doughnut? Tracing the pathway and conditions of its rise(2023) Wiemer, BjörnOf similative origin, Polish jakoby derives from the connective jako ‘how, that’ univerbated with the irrealis enclitic by. From the earliest attested stages (late 14th century) into the 17th century, jakoby was used as a comparison marker and as a subordinator of manner or purpose clauses. The former use has persisted, and the latter was ousted. After the 16th century jakoby further evolved into a reportive marker, as a particle or complementizer. Contrary to what pathways explaining the connection between similative and evidential marking would suggest, jakoby’s now predominant function as a reportive marker was apparently not prepared by inferential use, nor was its complementizer function mediated by a purpose function. Instead, purpose and reportive complementizers belong to different “branches”, both of which can be motivated by an indiscriminate similative-manner function. The evidence in favor of this derives from a systematic evaluation of extant research and a corpus study covering almost the entire period from 1600 to our day. A crucial moment to understanding jakoby’s functional changes is the insight that similatives can acquire propositional scope prior to entering the evidential domain and marking a metonymic relation between speech acts and epistemic attitudes expressed by the former.Item Zeitschriftenaufsatz Open Access Supersizing axions with small size instantons(2022) Kivel, Alexey; Laux, Julien; Yu, FelixWe construct a new framework to calculate the enhancement of axion masses and concomitant effects on axion-meson mixing arising from small size instantons (SSIs), which originate in models featuring an extended color gauge symmetry. The framework is based on an explicit evaluation of ‘t Hooft determinantal operators that partition into instanton amplitudes, affording a more precise determination of the axion-diphoton coupling than previous results. Using an explicit model first presented in ref. [1], we demonstrate that axions solving the strong CP problem can have electroweak scale masses and higher, driven by SSI effects. Such collider axions are prime targets for resonance searches at the Large Hadron Collider and afford a unique anchor for motivating extended color symmetries.Item Zeitschriftenaufsatz Open Access Axion couplings in gauged U(1)' extensions of the standard model(2023) Kivel, Alexey; Laux, Julien; Yu, FelixWe explore the effective theory of an axion in a gauged baryon number symmetry extension of the Standard Model (SM), where the axion is realized from a Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model construction. Integrating out the anomalons realizes a pattern of effective Wilson coefficients reflecting the factorization between the anomalous Peccei-Quinn and gauged baryon number symmetries. We construct and analyze the chiral transformation invariance of the axion effective theory, accounting for possible flavor-violating axion couplings. We calculate and study the unique phenomenology of the axion and Z′ boson, and we present the current collider limits on these particles in the {mZ′,gB}, {ma, Gaγγ}, and {ma,f−1a} planes.Item Zeitschriftenaufsatz Open Access Sterile neutrinos as dark matter candidates(2022) Kopp, JoachimIn these brief lecture notes, we introduce sterile neutrinos as dark matter candidates. We discuss in particular their production via oscillations, their radiative decay, as well as possible observational signatures and constraints.Item Zeitschriftenaufsatz Open Access De Sitter scattering amplitudes in the Born approximation(2022) Ferrero, Renata; Ripken, ChrisWe present a covariant framework to compute scattering amplitudes and potentials in a de Sitter background. In this setting, we compute the potential of a graviton-mediated scattering process involving two very massive scalars at tree level. Although the obtained scattering potential reproduces the Newtonian potential at short distances, on Hubble- size length scales it is affected by the constant curvature: effectively, it yields a repulsive force at sub-Hubble distances. This can be attributed to the expansion of the de Sitter universe. Beyond the de Sitter horizon, the potential vanishes identically. Hence, the scattering amplitude unveils the geometric properties of de Sitter spacetime in a novel and nontrivial way.Item Zeitschriftenaufsatz Open Access Excited state energy landscape of phosphorescent group 14 complexes(2023) Sikora, Philipp; Naumann, Robert; Förster, Christoph; Heinze, KatjaGreat progress has been achieved on phosphorescent or photoactive complexes of the Earth-abundant transition metals, while examples for phosphorescent heavy main group element complexes are rare, in particular for group 14 complexes in the oxidation state +II. The known compounds often show only weak phosphorescence with fast non-radiative deactivation. The underlying photophysical processes and the nature of the phosphorescent electronic states have remained essentially unexplored. The present combined photophysical and theoretical study on tin(II) and lead(II) complexes E(bpep) with the dianionic tridentate ligand bpep2− (E = Sn, Pb; H2bpep = 2-[1,1-bis(1H-pyrrol-2-yl)ethyl]pyridine) provides unprecedented insight in the excited state energy landscape of tetrel(II) complexes. The tin complex shows green intraligand charge transfer (ILCT) phosphorescence both in solution and in the solid state. In spite of its larger heavy-atom effect, the lead complex only shows very weak red phosphorescence from a strongly distorted ligand-to-metal charge transfer (LMCT) state at low temperatures in the solid state. Detailed (TD-)DFT calculations explain these observations and delineate the major path of non-radiative deactivation via distorted LMCT states. These novel insights provide rational design principles for tetrel(II) complexes with long-lived phosphorescence.Item Zeitschriftenaufsatz Open Access Fluvial activity of the late-glacial to Holocene “Bergstraßenneckar” in the Upper Rhine Graben near Heidelberg, Germany – first results(2022) Engel, Max; Henselowsky, Felix; Roth, Fabian; Kadereit, Annette; Herzog, Manuel; Hecht, Stefan; Lindauer, Susanne; Bubenzer, Olaf; Schukraft, GerdThe term “Bergstraßenneckar” (BSN) refers to an abandoned course of the river Neckar. It flowed in a northern direction east of the river Rhine in the eastern part of the northern Upper Rhine Graben in southwestern Germany. The former meandering course merged with the Rhine ca. 50 km further north of the site of the present-day confluence near Mannheim. The palaeo-channels are still traceable by their depressional topography, in satellite images and by the curved boundaries of adjacent settlements and land parcels. In the plan view, satellite and aerial images reveal a succession of meander bends, with older bends being cut off from younger channels. Based on stratigraphic investigations of the channel infill in the northern part of the BSN, fluvial activity is assumed from ca. 14 500 years ago until the onset of the Holocene. We present results of the first stratigraphic investigations at two sites in the southern part of the BSN near Heidelberg (Rindlache, Schäffertwiesen), together with results from granulometric, carbonate and organic content analyses, as well as electrical resistivity tomography (ERT) measurements. The data clearly show a change from high-energy fluvial bedload (sand, gravel) to low-energy fluvio-limnic suspended load (organoclastic and calcareous mud) and to peat formation. Radiocarbon dating indicates a time lag of ca. 1500 years between the cut-off meander site (Schäffertwiesen) and the younger site (Rindlache) that was possibly still active until the present-day confluence near Mannheim was established and the BSN eventually became abandoned. Our preliminary data conform with the pedo-sedimentary evidence from the northern BSN, but slight differences in the stratigraphic pattern of the youngest channels are identified: whilst for the younger channel sections of the northern BSN the channel-bottom facies (sand, gravel) is directly overlain by peat, the channel at Rindlache shows substantial intervening mud deposition, which is interpreted as suspension load from flooding by the new Neckar channel nearby. The study shows that more chronostratigraphic data from channel sections of the southern BSN are needed to better constrain the timing of the fluvial activity and to decipher the reasons for the abandonment of the BSN. These data are also necessary to better understand the pattern of temporary reactivation of the BSN channels across the Holocene and their usage by humans, which can be deduced from historical sources and archaeological data.Item Zeitschriftenaufsatz Open Access Studies on the H → bb cross section measurement at the LHeC with a full detector simulation(2022) Behera, Subhasish; Brickwedde, Bernard; Schott, MatthiasThe future Large Hadron electron Collider (LHeC) would allow collisions of an intense electron beam with protons or heavy ions at the High Luminosity-Large Hadron Collider (HL-LHC). Owing to a center of mass energy greater than a TeV and very high luminosity (∼1 ab−1), the LHeC would not only be a new generation collider for deep-inelastic scattering (DIS) but also an important facility for precision Higgs physics, complementary to pp and e+e− colliders. Previously, it has been found that uncertainties of 0.8% and 7.4% can be achieved on the Higgs boson coupling strength to b- and c-quarks respectively. These results were obtained in the fast simulation frameworks for the LHeC detector. Focusing on the dominant Higgs boson decay channel, H→bb, the present work aims to give a comparison of these results with a fully simulated detector. We present our results in this study using the publicly available ATLAS software infrastructure. Based on state-of-the art reconstruction algorithms, a novel analysis of the bb decay could be performed leading to an independent verification of the existing results to an exceptionally high precision.Item Zeitschriftenaufsatz Open Access Potential for a precision measurement of solar pp neutrinos in the Serappis experiment(2022) Bieger, Lukas; Birkenfeld, Thilo; Blum, David; Depnering, Wilfried; Enqvist, Timo; Enzmann, Heike; Gao, Feng; Genster, Christoph; Göttel, Alexandre; Grewing, Christian; Gromov, Maxim; Hackspacher, Paul; Hagner, Caren; Heinz, Tobias; Kampmann, Philipp; Karagounis, Michael; Kruth, Andre; Kuusiniemi, Pasi; Lachenmaier, Tobias; Liebau, Daniel; Liu, Runxuan; Loo, Kai; Ludhova, Livia; Meyhöfer, David; Müller, Axel; Muralidharan, Pavithra; Oberauer, Lothar; Othegraven, Rainer; Parkalian, Nina; Pei, Yatian; Pilarczyk, Oliver; Rebber, Henning; Robens, Markus; Roth, Christian; Sawatzki, Julia; Schweizer, Konstantin; Settant, Giulio; Slupecki, Maciej; Smirnov, Oleg; Stahl, Achim; Steiger, Hans; Steinmann, Jochen; Sterr, Tobias; Stock, Matthias Raphael; Tang, Jian; Theisen, Eric; Tietzsch, Alexander; Trzaska, Wladyslaw; van den Boom, Johannes; van Waasen, Stefan; Vollbrecht, Cornelius; Wiebusch, Christopher; Wonsak, Bjoern; Wurm, Michael; Wysotzki, Christian; Xu, Yu; Yegin, Ugur; Zambanini, Andre; Züfle, JanThe Serappis (SEarch for RAre PP-neutrinos In Scintillator) project aims at a precision measurement of the flux of solar pp neutrinos on the few-percent level. Such a measurement will be a relevant contribution to the study of solar neutrino oscillation parameters and a sensitive test of the equilibrium between solar energy output in neutrinos and electromagnetic radiation (solar luminosity constraint). The concept of Serappis relies on a small organic liquid scintillator detector (∼20 m3) with excellent energy resolution (∼2.5% at 1 MeV), low internal background and sufficient shielding from surrounding radioactivity. This can be achieved by a minor upgrade of the OSIRIS facility at the site of the JUNO neutrino experiment in southern China. To go substantially beyond current accuracy levels for the pp flux, an organic scintillator with ultra-low 14C levels (below 10−18 ) is required. The existing OSIRIS detector and JUNO infrastructure will be instrumental in identifying suitable scintillator materials, offering a unique chance for a low-budget high-precision measurement of a fundamental property of our Sun that will be otherwise hard to access.Item Zeitschriftenaufsatz Open Access The charm-quark contribution to light-by-light scattering in the muon (g − 2) from lattice QCD(2022) Chao, En-Hung; Hudspith, Renwick J.; Gérardin, Antoine; Green, Jeremy R.; Meyer, Harvey B.We compute the hadronic light-by-light scattering contribution to the muon g−2 from the charm quark using lattice QCD. The calculation is performed on ensembles generated with dynamical(u, d,s) quarks at the SU(3)f symmetric point with degenerate pion and kaon masses of around 415 MeV. It includes the connected charm contribution, as well as the leading disconnected Wick contraction, involving the correlation between a charm and a light-quark loop. Cutoff effects turn out to be sizeable, which leads us to use lighter-than-physical charm masses, to employ a broad range of lattice spacings reaching down to 0.039 fm and to perform a combined charm-mass and continuum extrapolation. We use the ηc meson to define the physical charm-mass point and obtain a final value of aHLbL,c μ = (2.8±0.5)×10−11, whose uncertainty is dominated by the systematics of the extrapolation. Our result is consistent with the estimate based on a simple charm-quark loop, whilst being free of any perturbative scheme dependence on the charm mass. The mixed charm–light disconnected contraction contributes a small negative amount to the final value.