Superconducting microresonators are powerful tools for measuring electron paramagnetic resonance in very small sample volumes. By keeping the thickness of the superconductor below a penetration depth, and aligning the DC magnetic field in the plane of the superconductor, high fields (much larger than the critical field) are possible. With transmission-line geometry resonators (typically...
Exchange processes which include conformational change, protonation/deprotonation, binding equilibria etc. are routinely studied by various 2D NMR techniques, e.g. EXSY, ZZ-exchange, CEST. In these techniques the information about exchange of nuclei between environments with different NMR parameters is obtained from the cross-peak development. Cross-peaks due to chemical exchange have been...
Tetracene is an archetypal material undergoing singlet fission—the generation of a pair of triplet excitons from one singlet exciton. Here, using time-resolved electron spin resonance, we show how the spin dynamics in tetracene crystals are influenced by temperature and morphology. Upon cooling from 300 to 200 K, we observe a switch between singlet fission and intersystem crossing generated...
Pulse dipolar EPR is widely used to study tertiary structure, dynamics and functional features of biomolecules. Nitroxides are commonly used spin labels. Trityl radicals or TAMs have appeared recently as an alternative source of spin labels using PDEPR[1]. In this presentation we compared functional properties of spin labels based on TAMs and nitroxides.PDEPR in combination with MD were used...
It is demonstrated that deep neural networks (DNN) are a powerful alternative to Tikhonov regularisation methods for the interpretation of double electron-electron resonance (DEER) data. Networks trained using large databases of synthetic DEER traces with carefully modelled distortions and noise are found to process previously unseen experimental data with results comparable to, and...
Many pathogens such as Vibrio cholerae use tripartite ATP-independent periplasmic (TRAP) transporters to scavenge N-acetyl- neuraminic acid (sialic acid) from host organisms. The sialic acid is then incorporated into the bacterial cell wall, as a disguise to protect against detection by the human immune system. TRAP transporters are a structural and functional mix between ABC transporters...
Spectral overlap, even at high field, is a problem generally encountered in many EPR studies. In the specific case of bulk-heterojunction (BHJ) organic solar cells (OSCs), the paramagnetic species of interest are light-induced radicals which are created as a pair after charge transfer at the interface between the donor polymer and molecular acceptor regions making up the BHJ blend. Hence, the...
Magnetic resonance observes spin transitions whose frequencies depend on magnetic field because spin is associated with magnetic moment. Allowed transitions involve a unit change of the magnetic quantum number. If the magnetic quantum number is not a good quantum number, other transitions can be partially allowed. The transition moment of such “forbidden” transitions depends on magnetic field....
Microfluidics is a well-established technique to process, synthesize and analyse small amounts of materials for chemical, biological, medical, and environmental applications. Typically, it involve the use of reagents with volume that is smaller than ~1 microliter – ideally even nano- or pico-liter. Conventional electron spin resonance (ESR), is typically carried out with ~ 1 ml of sample,...
Nanobodies (i.e. single-domain antibodies) are promising new tools for in-cell applications due to their low molecular weight, protein- and state- specificity, nano- or sub-nano-molar affinity to their target and the possibility to be inserted into cells. We propose here the use of spin-labeled nanobodies as conformational reporters of wild type unlabeled proteins via DEER spectroscopy.
We...
Electron paramagnetic resonance (EPR) distance measurements provide highly accurate and precise geometric constraints. These have made valuable contributions to studies of the structures and conformations of biomolecules. Recently, application of double-histidine (dHis) motifs, coupled with CuII spin-labels has shown promise in even higher precision distance...
Electron-nuclear double resonance (ENDOR) and dynamic nuclear polarization (DNP) are two techniques based on polarization transfer between electron and nuclear spins. Despite differences in the experimental realization, their similarities rely on the detailed mechanism of hyperfine interactions. The lecture will give an overview of our recent developments in these two methods in solids (ENDOR)...
THz ESR under multi-extreme conditions, which covers the frequency region between 0.03 and 7 THz1, the temperature region between 1.8 and 300 K1, the magnetic field region up to 55 T1, and the pressure up to 1.5 GPa2, has been developed in Kobe. Firstly, we will show our recent developments of the torque magnetometry3 and mechanically...
Water and other polar molecules are known to absorb electromagnetic radiation and the absorption is particularly strong in the mm-Wave (mmW) range. Metal surfaces are also becoming increasingly lossy. These high dielectric losses represent the major challenge for constructing EPR and also DNP NMR probeheads suitable for accommodating samples with the maximum volume. While large samples can...