We believe that, in addition to nontrivial theoretical interest, the proposed work offers experimenters a reliable time interval in which the experimentally measured signal allows for a relatively simple interpretation uncomplicated by contributions from three-particle dynamical correlations of having spin nuclei in condensed matter.

Electron spins sense their environment via magnetic interactions. An important contribution stems from nuclear spins in their vicinity. They cause loss of coherence and thus reduce resolution of spectra obtained by experiments on electron spins and the efficiency of transferring electron-spin magnetization to other nuclear spins. Here we study how protons in trityl radicals contribute to coherence loss. Such coherence loss is slower in the presence of a strong microwave field.

Sensitivity is often a limiting factor in electron–nuclear double resonance (ENDOR). Here we demonstrate how using chirp radiofrequency pulses can improve ENDOR sensitivity up to 3–9 fold, with the strongest increase for broader lines often encountered in disordered solids for nuclei such as nitrogen and metals. The resulting drastic speedup in acquisition times also renders 2D ENDOR more feasible, as we demonstrate in TRIPLE, showing correlations with Cu hyperfine couplings.

Electron spin dynamics during microwave irradiation are of increasing interest in electron paramagnetic resonance (EPR) spectroscopy. Here, we show that these dynamics can be probed by modern pulsed EPR experiments that use shaped microwave pulses. Combined with spin dynamics simulations, these results provide a starting point for optimizing existing EPR experiments and for developing new pulse sequences.

A method is presented which can be used to find analytical equations describing the behavior of a system of nuclear spins, even for moderately complex problems. The method does not use any approximation techniques. Some examples are given to illustrate the application. Despite the undoubted success of numerical methods, analytical results are often more suitable than numerical results for promoting physical understanding in teaching and scientific discussion.

A new pulse electron paramagnetic resonance method is presented to quantify the local nuclear environment of an electron spin centre. We provide a detailed assessment of this technique. We review the theoretical principles, discuss the data analysis and demonstrate an application to a spin-labelled macromolecule supported by in silico modelling. The method can be applied to the characterization of heterogeneous systems, such as unstructured or semi-structured (bio)macromolecules.