Teilbibliothek Naturwissenschaften: Chemie

Publikationen

Veröffentlichungen der AG Gräfe
Teilbibliothek Naturwissenschaften: Chemie
Foto: Jan-Peter Kasper (Universität Jena)

Referierte Publikationen

Bücher und Buchkapitel

  • Markus Kitzler und Stefanie Gräfe (Eds.),
    Ultrafast Dynamics Driven by Intense Light Pulses.Externer Link
    Springer Series on Atomic, Optical, and Plasma Physics, 978-3-319-20173-3 (2016).
  • Dirk Bender, Leticia González und 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).

Sonstige Publikationen

54 Publikationen filtern

Die Publikationen filtern

Hervorgehobene Autoren sind Angehörige der Universität Jena.

  1. eminus — Pythonic electronic structure theory

    ErscheinungsjahrErschienen 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.
    Universitätsbibliographie Jena:
    fsu_mods_00019240Externer Link

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

    ErscheinungsjahrErschienen in:ChemCatChem: heterogeneous & homogeneous & bio- & nano-catalysis A. Abbas, C. Kasahara, Y. Chen, M. Oschatz, S. Gräfe, W. Weigand, A. Pannwitz
    Universitätsbibliographie Jena:
    fsu_mods_00025047Externer Link

  3. Attosecond core-level absorption spectroscopy reveals the electronic and nuclear dynamics of molecular ring opening

    ErscheinungsjahrErschienen in:Nature Photonics S. Severino, K. Ziems, M. Reduzzi, A. Summers, H. Sun, Y. Chien, S. Gräfe, J. Biegert
    Universitätsbibliographie Jena:
    fsu_mods_00012809Externer Link

  4. Imaging Ultrafast Dissociation Dynamics: OCS & Roaming in Formaldehyde

    ErscheinungsjahrErschienen in:Proceedings of the 8th International Conference on Attosecond Science and Technology T. Endo, S. Neville, K. Ziems, P. Lassonde, C. Qu, B. Schmidt, H. Fujise, M. Fushitani, A. Hishikawa, S. Gräfe, P. Houston, J. Bowman, M. Schuurman, F. Légaré, H. Ibrahim
    Upon photoexcitation, molecules break apart, following different dissociation reactions. We can image these dissociation pathways using Coulomb explosion imaging (CEI) and sometimes we can control them using asymmetric laser fields. In the formaldehyde molecule, we can see fragments following the direct, conventional dissociation path, as well as fragments deviating from this minimum energy path. So-called roaming fragments or “roamers” explore the potential energy landscape in a statistical manner and could be directly captured in real-time, despite the signal’s statistical character. This is possible due to the single-molecule sensitivity of CEI and we could show that the onset of roaming occurs actually several orders of magnitude earlier than previously expected. In the polar molecule OCS we go one step further by controlling the fragmentation process using two-color asymmetric laser fields. In addition to expected direct ionization effects, we also see post-ionization contributions, which are usually not visible in heavy polar molecules. We thus show in two different examples that CEI provides the means to extract new, unexpected pathways, which would otherwise remain hidden underneath a strong background.
    Universitätsbibliographie Jena:
    fsu_mods_00011567Externer Link

  5. Computational studies of transition metal catalysts and the exploration of structure-reactivity relationships using machine learning approaches

    Erscheinungsjahr T. Huang
    Universitätsbibliographie Jena:
    fsu_mods_00016980Externer Link

  6. Intense-laser-field ionization with nondipole corrections

    Erscheinungsjahr R. Kahvedžić
    This dissertation presents a theoretical investigation of the impact of nondipole corrections on photoelectron momentum distributions resulting from the interaction of atomic targets with intense mid-infrared laser fields. Beginning with the establishment of a theoretical framework based on the strong-field approximation, we subsequently derive transition amplitudes with nondipole corrections. These amplitudes are thereafter adapted for numerical integration and saddle-point approximation to analyze the effects nondipole corrections have on photoelectron momentum distributions. Therein, both linearly and circularly polarized laser fields are considered. In linearly polarized fields, nondipole corrections lead to momentum shifts along the field-propagation direction and alterations in momentum-distribution-peak yields. Considering solely direct photoelectrons, individual ionization pathways originating within one optical cycle lead to positive shifts along the field-propagation direction. However, the interference of individual ionization pathways leads to an oscillatory behavior which, in the low-energy region of the spectrum, crosses to negative values, thereby inducing a negative shift along the field-propagation direction. In contrast, photoelectrons that undergo rescattering show a negative shift even at the level of individual ionization pathways, caused by an intricate interplay between the rescattering event and the included nondipole corrections. Moreover, the nondipole corrections deform the ring-shaped structures in the high-energy regions of photoelectron momentum distribution into rotated elliptic structures. For circularly polarized fields, where recollision events are suppressed, the study demonstrates a distortion of the photoelectron momentum distribution as well as its shift along the field-propagation direction. The sole ionization pathway leads to an exclusively positive shift along the field-propagation direction.
    Universitätsbibliographie Jena:
    fsu_mods_00018033Externer Link

  7. From Lithium and Sodium Superoxides to Singlet-Oxygen – Insights into the Mechanism of Dissociation Using SHARC-MD

    ErscheinungsjahrErschienen in:ChemPhysChem: a European journal of chemical physics and physical chemistry D. Pietruschka, A. Zaichenko, M. Richter, S. Gräfe, D. Mollenhauer
    The formation of highly reactive singlet oxygen from alkaline superoxides presents an important reactivity of this component class. Investigations of the reaction paths such as disproportionation of LiO₂ and NaO₂ have been presented. Furthermore, the dissociation of these superoxide systems have been discussed as an alternative reaction channel that also allows the formation of singlet oxygen. Here, we present a fundamental study of the electronic nature and dissociation behaviour of the alkali superoxides. The molecular systems were calculated at the CASSCF/CASPT2-level of theory. We determined the minimum energy crossing points along the dissociation required to form triplet oxygen ³O₂ and singlet oxygen ¹O₂. Building on these results, a surface-hopping AIMD-simulation was performed employing the SHARC program package to follow the electronic transitions along the minimum energy crossing points during the dissociation. The feasibility of populating the electronic state corresponding to the formation of singlet oxygen during dissociation was demonstrated. For LiO₂, 6.85 % of the trajectories were found to terminate under formation of ¹O₂, whereas for NaO₂ only 1.68 % of the trajectories ended up in ¹O₂ formation. This represents an inverse trend to that reported in the literature. This observation suggests that the dissociation is a viable, monomolecular reaction path to ¹O₂ that complements the disproportionation pathway.
    Universitätsbibliographie Jena:
    fsu_mods_00018306Externer Link

  8. Assessing plasmon-induced reactions by a combined quantum chemical-quantum/classical hybrid approach

    ErscheinungsjahrErschienen in:Nanoscale S. Ehtesabi, M. Richter, S. Kupfer, S. Gräfe
    Plasmon-driven reactions on metal nanoparticles feature rich and complex mechanistic contributions, involving a manifold of electronic states, near-field enhancement, and heat, among others. Although localized surface plasmon resonances are believed to initiate these reactions, the complex reactivity demands deeper exploration. This computational study investigates factors influencing chemical processes on plasmonic nanoparticles, exemplified by protonation of 4-mercaptopyridine (4-MPY) on silver nanoparticles. We examine the impact of molecular binding modes and molecule-molecule interactions on the nanoparticle's surface, near-field electromagnetic effects, and charge-transfer phenomena. Two proton sources were considered at ambient conditions, molecular hydrogen and water. Our findings reveal that the substrate's binding mode significantly affects not only the energy barriers governing the thermodynamics and kinetics of the reaction but also determine the directionality of light-driven charge-transfer at the 4-MPY-Ag interface, pivotal in the chemical contribution involved in the reaction mechanism. In addition, significant field enhancement surrounding the adsorbed molecule is observed (eletromagnetic contribution) which was found insufficient to modify the ground state thermodynamics. Instead, it initiates and amplifies light-driven charge-transfer and thus modulates the excited states’ reactivity in the plasmonic-molecular hybrid system. This research elucidates protonation mechanisms on silver surfaces, highlighting the role of molecular-surface and molecule-molecule-surface orientation in plasmon-catalysis.
    Universitätsbibliographie Jena:
    fsu_mods_00015688Externer Link

  9. Tailoring phosphine ligands for improved C-H activation: insights from Δ-machine learning

    ErscheinungsjahrErschienen in:Digital Discovery: a journal for new thinking on machine learning, robotics and AI T. Huang, R. Geitner, A. Croy, S. Gräfe
    Transition metal complexes have played crucial roles in various homogeneous catalytic processes due to their exceptional versatility. This adaptability stems not only from the central metal ions but also from the vast array of choices of the ligand spheres, which form an enormously large chemical space. For example, Rh complexes, with a well-designed ligand sphere, are known to be efficient in catalyzing the C-H activation process in alkanes. To investigate the structure-property relation of the Rh complex and identify the optimal ligand that minimizes the calculated reaction energy ΔE of an alkane C-H activation, we have applied a Δ-machine learning method trained on various features to study 1743 pairs of reactants (Rh(PLP)(Cl)(CO)) and intermediates (Rh(PLP)(Cl)(CO)(H)(propyl)). Our findings demonstrate that the models exhibit robust predictive performance when trained on features derived from electron density (R² = 0.816), and SOAPs (R² = 0.819), a set of position-based descriptors. Leveraging the model trained on xTB-SOAPs that only depend on the xTB-equilibrium structures, we propose an efficient and accurate screening procedure to explore the extensive chemical space of bisphosphine ligands. By applying this screening procedure, we identify ten newly selected reactant-intermediate pairs with an average ΔE of 33.2 kJ mol−¹, remarkably lower than the average ΔE of the original data set of 68.0 kJ mol−¹. This underscores the efficacy of our screening procedure in pinpointing structures with significantly lower energy levels.
    Universitätsbibliographie Jena:
    fsu_mods_00013567Externer Link

  12. Molecular Dyad vs Multi-Component Approach-Photocatalytic Hydrogen Evolution by Combining Oligothiophene Photosensitizers with [FeFe]-Hydrogenase Mimics

    ErscheinungsjahrErschienen in:ChemCatChem: heterogeneous & homogeneous & bio- & nano-catalysis C. Kasahara, K. Rediger, M. Micheel, P. Liebing, G. Stefanie, S. Kupfer, M. Wächtler, W. Weigand
    A molecular dyad (PS-CAT) consisting of a metal-free photosensitiser (PS) and a [FeFe]-hydrogenase-inspired [Fe₂S₂] cluster (CAT) has been synthesized for hydrogen evolution under visible light irradiation. The electrochemical properties of PS-CAT in the absence and presence of acid were investigated by CV and IR-SEC. The ground state and excited state photophysical properties of PS and PS-CAT, and the non-chemically connected reference system [PS, CAT] were investigated to elucidate the effect of a covalent linkage between PS and CAT on the electronic communication and hence on the catalytic performance. The photo-relaxation pathway of PS-CAT was revealed computationally by scalar-relativistic time-dependent density functional theory simulations. These studies are complemented by comparative analyses of photocatalytic hydrogen evolution between PS-CAT and [PS, CAT] under visible light irradiation.
    Universitätsbibliographie Jena:
    fsu_mods_00013017Externer Link
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