Michael Dieter Wörle

Last Name

Wörle

First Name

Michael Dieter

ORCID

0000-0001-8087-5779

Organisational unit

02514 - Laboratorium für Organische Chemie / Laboratory of Organic Chemistry

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Publications 1 - 9 of 9

Unraveling the formation of Tb/Pd films by coupled reduction as targets for heavy ion-beam irradiation
Cerboni, Noemi; Szekér, Balazs; Dressler, Rugard; et al. (2025)
Journal of Alloys and Compounds
This study provides insights into the formation of Tb/Pd films produced by electroplating in combination with the so-called coupled reduction technique. The use of 149Tb as an α-emitting radionuclide enabled for the first time the study of the distribution of Tb across the surface and along the thickness of the Pd bulk by means of radiography and α-spectroscopy combined with Monte Carlo simulations of the energy loss of emitted α-particles, respectively. Additionally, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were employed for surface analysis, whereas X-ray diffraction provided conclusive evidence of the formed crystalline phases. The obtained results indicate the formation of either the intermetallic phase TbPd3 or a Tb/Pd solid solution, depending on the heating time and temperature as well as the local Tb/Pd atomic ratio. These insights pave the way to the production of stable targets for heavy ion-beam irradiations as well as other applications.
Method of precise optical crystal alignment by tilting the diamond anvil cell
Rusanov, Eduard; Wörle, Michael Dieter; Kovalenko, Maksym V. (2025)
Journal of Applied Crystallography
A new, accurate method for fast and precise optical alignment of crystals in a diamond anvil cell (DAC) on a diffractometer has been developed. It enables highly accurate crystal alignment within instruments with a Boehler-Almax DAC design, achieving precision better than 0.02 mm easily. Other advantages of this method are simplicity, speed and instant visual feedback when aligning the crystal. This method employs Snell's law, which relates the angles of incidence and refraction of light passing through different media to estimate the crystal position within the DAC by measuring the apparent transverse displacement of the crystal image at various viewing angles after rotating the DAC by 180°. This information allows for fine-tuning of the crystal alignment within the DAC, ensuring optimal conditions for high-pressure diffraction experiments.
Temperature‑Dependent 207Pb Nuclear Magnetic Resonance Spectroscopy: A Spectroscopic Probe for the Local Electronic Structure of Lead Halide Perovskites
Sabisch, Sebastian; Aebli, Marcel; Kanak, Andrii; et al. (2025)
Chemistry of Materials
Lead halide perovskites (LHPs) have garnered considerable interest, owing to their advantageous optoelectronic properties and ease of synthesis. However, understanding their intricate structure-property relationships remains challenging, for both bulk and nanoscale forms, such as colloidal quantum dots (QDs). In this study, in addition to conventional characterization by X-ray diffraction and optical absorption, we show that variable temperature solid-state nuclear magnetic resonance spectroscopy, complemented by computational modeling, provides unique insight into the local coordination geometry and electronic structure of LHPs in relation to the moderate change in composition or materials morphology. For CsPbBr3 and FAPbBr3 in the form of QDs and bulk, we uncover nuanced disparities between their orthorhombic and on-average cubic structures, respectively, reflected in their temperature-dependent 207Pb chemical shifts and optical band gaps. Specifically, the mode of thermal expansion, be it the increase of the Pb-Br-Pb angles in the orthorhombic structure or the elongation of the Pb-Br bonds in a cubic lattice, gives rise to an increase of the chemical shift by 0.63 or 1.53 ppm/K and optical band gap by 0.18 or 0.66 meV/K, respectively. Identifying the chemical shift as a spectroscopic descriptor, in particular as a lattice ruler, is highly instrumental also for LHP QDs, capturing the difference between CsPbBr3 and FAPbBr3. In a broader perspective, establishing relations across spectroscopic and structural descriptors for diverse LHP compositions and morphologies paves the way for informed design strategies in next-generation optoelectronic devices.
Single-Phase Lithiation in Iron Hydroxy Fluorides with Pyrochlore Structure
Baumgärtner, Julian; Stoian, Dragos C.; Marshall, Kenneth P.; et al. (2025)
ACS Energy Letters
3D transition metal fluorides have long been recognized as appealing low-cost, high-energy-density cathode materials for Li-ion batteries, but their conversion-type lithiation mechanism induces structural and morphological changes, limiting their cycling stability. Our findings now suggest that metal fluorides may undergo single-phase lithiation when crystallized in a pyrochlore structure, enabled by the presence of Li-ion storage sites within interconnected hexagonal channels. By conducting a detailed analysis of pyrochlore iron(III) hydroxy fluorides during lithiation using operando X-ray absorption spectroscopy, X-ray total scattering, and electron microscopy, we provide evidence for a possible single-phase lithiation mechanism and robust structural stability. These results challenge the traditional view of conversion-type lithiation in metal fluorides and highlight their potential for achieving high cycling stability and eventual commercialization in Li-ion batteries.
Ordering Principles in Niobium Tungsten Oxides of the Tetragonal Tungsten Bronze Type
Krumeich, Frank; Wörle, Michael Dieter (2025)
Zeitschrift für anorganische und allgemeine Chemie
In the system Nb2O5/WO3, phases with structures related to the tetragonal tungsten bronze (TTB) type occur at three well-defined compositions: Nb2WO8 (two modifications), Nb8W9O47, and Nb4W7O31. Samples with a deviating ratio O/Sigma M (M = Nb,W) form intricate intergrowths of Nb8W9O47 with the other phases and with less-ordered regions. Depending on the state of order, X-ray powder diffraction patterns show the reflections of the threefold TTB superstructure of Nb8W9O47 or only those of the basic TTB structure. In contrast, the evaluation of high-resolution electron microscopy images (here: HAADF-STEM) reveals the real structure. While in O-rich samples, segregations of ReO3-type structure appear, the variation of composition in the Nb-rich range is realized by a flexible but never completely random occupation of pentagonal tunnels in a perfectly ordered TTB substructure. The long searched-for phase Nb12W11O63 has not been obtained yet though a structure with this composition occurs in nanodomains.
Water Serving as Cocatalyst for the Highly Efficient Homogeneously Catalyzed Conversion of N₂O/H₂ Mixtures with Optimized Rhodium NHC Complexes
Nappen, Sven Thomas; Gamboa Carballo, Juan José; Tschanen, Esther; et al. (2025)
Angewandte Chemie. International Edition
Nitrous oxide (N2O) is a valuable oxygen/nitrogen transfer reagent but reactions with N2O are challenging due to its inertness. Consequently, it accumulates in the atmosphere, and because it is both an ozone-depleting reagent and potent green-house gas, effective mitigation methods become important. This study presents rhodium(I) amido bis(olefin) N-heterocyclic carbene complexes [Rh(trop2N)(NHC)] as robust homogeneous catalysts for the direct hydrogenation of N2O. Kinetic experiments and DFT calculations show that increasing π-acidity of the NHC and the presence of water significantly enhance the catalytic efficiency. The rhodium-amido bond facilitates cooperative H2-cleavage and oxygen atom transfer from N2O. The catalyst is regenerated with the loss of water from the hydroxide intermediate [Rh(OH)(trop2NH)(NHC)], which forms a dimeric complex with a central bridging hydrated hydroxide ligand [H3O2]−. Water facilitates dinitrogen (N2) loss from an intermediate containing an oxy-diazene ligand [H–N=N–O]−. The optimized catalyst achieves a TON > 230,000 and TOF > 1,300 h−1.
Surface Enhanced Nuclear Magnetic Resonance Spectroscopy at Solid-Liquid Interfaces Using Overhauser Dynamic Nuclear Polarization
Rao, Yu; Gioffrè, Domenico; Levien, Marcel; et al. (2025)
Journal of the American Chemical Society
While solid–liquid interfaces are ubiquitous, detecting the associated surface sites under ambient conditions remains a grand challenge. Here, we demonstrate an approach to efficiently enhance the NMR signals of solid surfaces at the solid–liquid interface at ambient temperature that is based on exchange mediated Overhauser effect dynamic nuclear polarization (OE-DNP). We use this approach to obtain DNP enhancements for the 31P signals of PPh3 ligands interacting with Rh(I) surface sites, in prototypical silica-supported materials prepared via surface organometallic chemistry. Efficient enhancement (εi) is obtained under ambient conditions simultaneously at the surface (εsurface = 20–30) and in solution (εsolution up to 50), enabling detection of species both at the surface and in solution, opening the possibility to monitor surface and interfacial chemistry.
Stepwise and reversible assembly of [2Fe-2S] rhombs to [8Fe-8S] clusters and their topological interconversions
Grunwald, Liam; Weber, Micha; Seng, Henrik; et al. (2025)
Nature Chemistry
Among all enzymatic metallocofactors, those found in nitrogenases, the P and L or M clusters, stand out for their intricate structures. They are assembled by proteins of the Nif gene cluster from Fe₂S₂ rhombs-the smallest building blocks in FeS cluster chemistry-through a sequence of reactions constructing a Fe₈S₈ precursor. To advance our understanding of how enzymes selectively build such elaborate inorganic molecules, here we parallel the biosynthetic pathway by reporting the rational stepwise assembly of [Fe8S8]ᵐ⁺ (m = 2, 4, 6) clusters from [Fe₂S₂]²⁺ rhombs within an extensive cyclic synthetic network. A [Fe₈S₈]⁴⁺ cluster of unique topology is identified, for which we coin the term ‘interlocked’ double cubane. As a molecular analogue of the NifB K cluster, a proposed precursor to both the P and L or M clusters, its preparation and the characterization of all related intermediates, offers fundamental insights into the molecular mechanisms governing the assembly of both biogenic and synthetic FeS clusters.
Crystal structure of calciumpermanganate tetrahydrate, Ca(MnO₄)₂⋅4H₂O, CaH₈Mn₂O₁₂
Wächter, Florian; Wörle, Michael Dieter; Budnyk, Serhiy; et al. (2012)
Zeitschrift für Kristallographie. New Crystal Structures

Publications 1 - 9 of 9

Michael Dieter Wörle

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