Abstracted/indexed

Magnetic resonance detectors require a high degree of precision to be useful. Their design must e.g. carefully weigh field strength and field homogeneity, to find the best compromise. Here we show that inverse computational design is a viable method to find such a compromise. Apart from the electromagnetic field solution, the simulation program also determines the boundary between insulating and conducting material, and moves the material boundaries around until the compromise is best satisfied.

Here we demonstrate that Electron Spin Resonance (ESR) spectroscopy at millikelvin temperatures can be performed with a spectrometer comprised of a thin-film superconducting resonator and Josephson Parametric Amplifier (JPA) with sufficient bandwidth to detect Electron Spin Echo Envelope Modulation (ESEEM) while maintaining high spin-detection sensitivity.

Resonant pulses in a spin-lock frame are used to select parts of the rf-field distribution in NMR experiments. Such pulses can be implemented in a straight forward way and arbitrary shaped pulses can be used. We show an application of such pulses in homonuclear decoupling where restricting the amplitude distribution of the rf field leads to improved performance.

We have studied spin dynamics in nuclear spin systems at low magnetic fields, where “strong coupling” among nuclear spins of the same kind, here C-13, is expected. Such conditions are known to be favorable for coherent polarization transfer. However, to our surprise, interactions to other nuclei, here protons, lead to breakdown of the strong coupling conditions. By using a two-field NMR approach, we are able to manipulate low-field spin dynamics and reintroduce strong coupling.

We explored hydrogenation reaction with para-spin isomer of hydrogen molecule as a source of nuclear singlet state. As a product of this reaction, the state was populated between two protons of the methylene group. We have shown that utilizing the long-lived properties of such nuclear spin state a high nuclear spin polarization can be accumulated. To explain this effect we have given a kinetic model which could be potentially applied for similar schemes involving spin dynamics in chemistry.

With a pulsed dipolar EPR technique named Double Electron-Electron Resonance, we measure nanometer distances between spin labels attached to biomolecules. If more than one spin type is present (A and B), we can separately address AA, AB and BB distances via distinct spectroscopic channels, increasing the information content per sample. Here we investigate the appearance of unwanted channel crosstalks and suggest ways to identify and suppress them, thereby increasing signal fidelity.

Dipolar EPR spectroscopy methods such as DEER provide data on how proteins change shape, thus giving detailed insight into how proteins work. We present DeerLab, a comprehensive open-source software for completely and reliably analyzing the associated data. The software implements a series of theoretical and algorithmic innovations and thereby improves the quality and reproducibility of data analysis.

For the first time, a three-dimensional map of the distribution of water in a test sample has been obtained from the random radio signal (spin noise) emitted spontaneously by hydrogen nuclei in a magnetic field with varying field gradients. A special variant of a projection-reconstruction algorithm has been developed for noise data, which allows one to adjust the image quality between high-resolution/low-contrast and low-resolution/high-contrast from the same previously recorded spin noise data.