Teilbibliothek Naturwissenschaften: Chemie

Publications

Teilbibliothek Naturwissenschaften: Chemie
Image: Jan-Peter Kasper (University of Jena)

Peer reviewed publications

Books and book chapters

  • Markus Kitzler and Stefanie Gräfe (Eds.),
    Ultrafast Dynamics Driven by Intense Light Pulses.External link
    Springer Series on Atomic, Optical, and Plasma Physics, 978-3-319-20173-3 (2016).
  • Dirk Bender, Leticia González and Stefanie Gräfe,
    Short Introduction to Atomic and Molecular Configuration.
    in: Handbook of Biophotonics, J. Popp, V. V. Tuchin, A. Chiou, S. Heinemann (Eds.), Wiley-VCH Weinheim, Vol. 1(Basics and Techniques), 39-86 (2011).

Other publications

118 Publikationen filtern

Die Publikationen filtern

Highlighted authors are members of the University of Jena.

  1. Semiconductor Bloch equations in Wannier gauge with well-behaved dephasing

    Year of publicationStatusReview pendingPublished in:Computer physics communications : an international journal and program library for computational physics and physical chemistry M. Thümmler, T. Lettau, A. Croy, U. Peschel, S. Gräfe
    The semiconductor Bloch equations (SBEs) with a dephasing operator for the microscopic polarizations are a well established approach to simulate high-harmonic spectra in solids. We discuss the impact of the dephasing operator on the stability of the numerical integration of the SBEs in the Wannier gauge. It is shown that the commonly used phenomenological approach to apply dephasing is ill-defined in the presence of band crossings and leads to artifacts in the carrier distribution. They are caused by rapid changes of the dephasing operator matrix elements in the Wannier gauge, which render the convergence of the simulation in the stationary basis infeasible. In the comoving basis, also called Houston basis, these rapid changes can be resolved, but only at the cost of a largely increased computation time. As a remedy, we propose a modification of the dephasing operator with reduced magnitude in energetically close subspaces. This approach removes the artifacts in the carrier distribution and significantly speeds up the calculations, while affecting the high-harmonic spectrum only marginally. To foster further development, we provide our parallelized source code.
    University Bibliography Jena:
    fsu_mods_00029532External link

  2. eminus — Pythonic electronic structure theory

    Year of publicationPublished in:SoftwareX W. Schulze, S. Schwalbe, K. Trepte, S. Gräfe
    In current electronic structure research endeavors such as warm dense matter or machine learning applications, efficient development necessitates non-monolithic software, providing an extendable and flexible interface. The open-source idea offers the advantage of having a source code base that can be reviewed and modified by the community. However, practical implementations can often diverge significantly from their theoretical counterpart. Leveraging the efforts of recent theoretical formulations and the features of Python, we try to mitigate these problems. We present eminus, an education- and development-friendly electronic structure package designed for convenient and customizable workflows, yet built with intelligible and modular implementations.
    University Bibliography Jena:
    fsu_mods_00019240External link

  3. Towards simultaneous imaging of ultrafast nuclear and electronic dynamics in small molecules

    Year of publicationPublished in:Scientific Reports S. Mhatre, Z. Dube, A. Staudte, S. Gräfe, M. Kübel
    When a chemical bond is broken, the molecular structure undergoes a transformation. An ideal experiment should probe the change in the electronic and nuclear structure simultaneously. Here, we present a method for the simultaneous time-resolved imaging of nuclear and electron dynamics by combining Coulomb explosion imaging with strong-field photoelectron momentum imaging. We study the dissociative photoionization of H₂ and N₂O using time-resolved photoion-photoelectron coincidence spectroscopy. The measured delay-dependent kinetic energy release clearly reveals the ultrafast nuclear dynamics. The transient changes in the electronic structure of the dissociating molecular ion are studied by solving the three-dimensional Schrödinger equation in the fixed-nuclei approximation. A detailed comparison of the numerical results to those from a simple imaging model is conducted. The numerical results reflect the evolution in the electron density in the molecular ion as its bond is first stretched and then breaks apart. While these details remain unresolved in the H₂ experiment, we demonstrate the sensitivity of the photoelectron signal to the site of electron localization following bond cleavage for the case of N₂O. Our work shows opportunities and challenges on the track towards capturing simple gas-phase chemical dynamics in complete molecular movies.
    University Bibliography Jena:
    fsu_mods_00023458External link

  4. Nonradiative transitions in molecular devices for energy conversion and storage

    Year of publication C. Zens
    University Bibliography Jena:
    fsu_mods_00026685External link

  5. Evaluating the contribution of electromagnetic nearfield gradients in TERS

    Year of publicationPublished in:Optics communications : a journal devoted to the rapid publication of contributions in the field of optics and interaction of light with matter A. Khodadadi, K. Fiederling, S. Kupfer, S. Gräfe
    University Bibliography Jena:
    fsu_mods_00025747External link

  6. Selective Light-Driven CO₂ to CO Reduction by a [FeFe]-Hydrogenase Mimic in Water

    Year of publicationPublished in:ChemCatChem: heterogeneous & homogeneous & bio- & nano-catalysis A. Abbas, C. Kasahara, Y. Chen, M. Oschatz, S. Gräfe, W. Weigand, A. Pannwitz
    University Bibliography Jena:
    fsu_mods_00025047External link

  7. Probing Metal Tip-Induced Bond Weakening of a Reactive Alkyne Center Aligned via a Rigid Triphenylmethane-Based Tripod on Au(111) by TERS and DFT

    Year of publicationStatusReview pendingPublished in:Journal of Raman spectroscopy : JRS ; an international journal for original work in all aspects of Raman Spectroscopy, including higher order processes and also Brillouin- and Rayleigh scattering G. Li, S. Mennicken, L. Zhu, S. Ehtesabi, T. Reichenauer, S. Kupfer, D. Schäfer, S. Mehrparvar, G. Haberhauer, Y. Zhang, S. Gräfe, S. Schlücker, Z. Dong
    The chemical reactivity of molecules can be controlled by a variety of effects, ranging from chemical reagents to purely physical stimuli. Metal tips employed in scanning probe microscopy are an elegant tool to manipulate reactive centers in single molecules. However, to achieve excellent control over distance and orientation, it is crucial to immobilize the reactive center and align it along the direction of the tip. Here, we aligned a reactive alkyne center via a rigid triphenylmethane-based tripod for upright adsorption on Au(111) for inducing bond weakening in the alkyne moiety by approaching a silver tip. Single-molecule ultrahigh vacuum low-temperature tip-enhanced Raman scattering was employed for probing tip-induced bond weakening in the gap distance range from 550 to 250 pm. Both the ≡C–H stretching at ~3330 cm−¹ and the dominant –C≡C– stretching peak at ~2130 cm−¹ exhibit a shift to smaller wavenumbers due to tip-induced bond weakening and an exponential increase in Raman intensity originating from the increased local electric field in the nanogap. To rationalize the underlying physical contributions and chemical effects of tip-induced bond weakening, density functional theory calculations for gap distances in the range 800 to 100 pm were performed. The computational results confirmed the presence of different gap distance regimes including the onset of Pauli repulsion for short distances; for the latter, the calculations additionally predict structural distortions of the terminal alkyne induced by the nearby metal tip. These findings allow us to set a lower limit for the tip–tripod gap distance in studies requiring an intact upright configuration of the alkyne-tripod, for example, electric field-induced chemistry.
    University Bibliography Jena:
    fsu_mods_00029568External link

  8. [FeFe]-hydrogenase mimic with organic photosensitizers for long-lived excited states and efficient photocatalytic H₂ production

    Year of publicationStatusReview pendingPublished in:Cell Reports Physical Science C. Kasahara, M. Farh, K. Rediger, P. Buday, S. Gräfe, M. Micheel, S. Kupfer, M. Wächtler, W. Weigand
    We report a [FeFe]-hydrogenase mimic complex bearing two organic photosensitizers ( PS-CAT , C₇₀H₄₄Fe₂N₂O₆S₆) aimed at achieving superior light-absorbing properties. PS-CAT is a dyad with two light-harvesting moieties ( PS ) and one catalytic center ( CAT ). The present study investigates the electro- and photo-reduction properties of PS-CAT , combining experimental and theoretical approaches to achieve a comprehensive understanding of the (photo)reduction mechanism of the dyad. To this aim, PS-CAT was studied by means of cyclic voltammetry, IR-spectroelectrochemistry, nanosecond-transient absorption, and scalar relativistic-time-dependent-density functional theory. The results reveal that the dyad can access the photo-excited state with a large absorption coefficient due to multiple PSs. Moreover, the PS-CAT produced long-lived excited species with a ligand-centered or charge-separated character by photon absorption. The subsequent quenching can produce the catalytically active reduced species. Furthermore, the photocatalytic activities of PS-CAT under visible light irradiation were examined, and the PS-CAT exhibited high efficiency (turnover frequency 33 h−¹) of H₂ generation as a PS -bearing [FeFe]-H₂ase mimic.
    University Bibliography Jena:
    fsu_mods_00029538External link

  9. Structural Control of Metal-Centered Excited States in Cobalt(III) Complexes via Bite Angle and π–π Interactions

    Year of publicationPublished in:Journal of the American Chemical Society P. Yaltseva, T. Maisuradze, A. Prescimone, S. Kupfer, O. Wenger
    CoIIIcomplexes have recently become an important focus in photophysics and photoredox catalysis due to metal-centered excited states with strong oxidizing properties. Optimizing chelate ligand bite angles is a widely used strategy to strengthen metal–ligand interactions in coordination complexes, with the resulting enhanced ligand fields often contributing to extended excited-state lifetimes that are advantageous for photochemical applications. We demonstrate that bite-angle optimization exerts the opposite effect on CoIIIpolypyridines compared to previously studied transition metal complexes, as polypyridine ligands function as π-donors to CoIIIrather than π-acceptors. Our findings reveal two counterintuitive paradigms: while bite-angle optimization weakens the ligand field in CoIIIcomplexes, the resulting lower-energy metal-centered excited states can be accompanied by extended excited-state lifetimes, driven by increased rigidification through intramolecular π–π interactions. These insights, along with additional experiments investigating the possibility of photoreactions from higher excited states, advance the current understanding of the photophysics and photochemistry of first-row transition metal complexes and highlight key distinctions from the more extensively studied photoactive complexes of second- and third-row transition metals.
    University Bibliography Jena:
    fsu_mods_00027038External link

  10. Machine Learning Models for Predicting Electronic Coupling in TEMPO/TEMPO+ Systems

    Year of publicationPublished in:The journal of physical chemistry C S. Mitra, C. Zens, S. Kupfer, A. Heuer, D. Diddens
    Organic radical batteries (ORBs) based on the TEMPO (2,2,6,6-tetramethylpiperidin-1-yl oxyl) radical have drawn significant attention, owing to their unique redox properties. A key factor influencing ORB’s redox properties, i.e., the kinetics of the electron transfer between the TEMPO–TEMPO⁺pairs, is the communication between the underlying redox-active states as given by the electronic coupling. However, due to the complex structure, predicting accurate electronic couplings for these pairs is computationally expensive and challenging. In this study, we introduce a machine learning (ML) workflow to predict the electronic coupling for TEMPO–TEMPO⁺pairs simply by their specific geometric orientations. For the ML models, a data set was generated through time-dependent density functional theory calculations coupled with the Generalized Mulliken Hush method to assess energies, (transition-)dipole moment, and couplings for specific TEMPO–TEMPO⁺configurations obtained from classical molecular dynamics simulations that mimic a realistic electrolyte environment. Our results demonstrate that, among the three ML models─linear regression, kernel ridge regression (KRR), and random forest─the KRR model, with its kernel-based approach, most effectively handles the correlated orientation-based descriptors. Moreover, our SHapley Additive exPlanations (SHAP)-based feature importance analysis indicates that multiple orientation factors jointly influence electronic coupling, rather than any single distance or angle dominating, with each parameter’s impact strongly contingent on the values of the others which is in agreement with previous studies computational by the consortium.
    University Bibliography Jena:
    fsu_mods_00027182External link

  11. Probing the performance of DFT in the structural characterization of [FeFe] hydrogenase models

    Year of publicationPublished in:Journal of computational chemistry : organic, inorganic, physical, biological P. Matczak, P. Buday, S. Kupfer, H. Görls, G. Mlostoń, W. Weigand
    University Bibliography Jena:
    fsu_mods_00017792External link

  12. DFT-Guided Synthesis, Electrochemical, and Photophysical Properties of Ruthenium(II) Polypyridyl Complexes Featuring Flavin-Inspired π-Extended Ligands

    Year of publicationPublished in:Chemistry: a European Journal N. Hagmeyer, N. Mroweh, A. Schwab, C. McManus, M. Varghese, J. Mouesca, S. Gambarelli, S. Kupfer, B. Dietzek-Ivanšić, M. Chavarot-Kerlidou
    University Bibliography Jena:
    fsu_mods_00025279External link
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