From a better use of instrumentation to new detection methods in NMR and EPR spectroscopy

NMR and EPR spectroscopy are two of the most important techniques to get quantitative, structural or dynamical information on molecular systems. After covering the fundamentals of these magnetic resonance techniques, this thesis explores ways to improve the usage of current spectrometers and to create new instruments altogether using different detection methods with quantum sensing. First, to deal with bandwidth and oscillating magnetic field limitations typically present for 19F nuclei in NMR or unpaired electrons in EPR, improved methods based on frequency-swept pulses are presented. The implementation of the CHORUS sequence in EPR spectroscopy is detailed. New pulse sequences, namely CHORUSCPMG, PROCHORUS and superposed frequency-swept pulses, are presented in the context of solution-state NMR spectroscopy. Then, on-the-fly optimisation is proposed as a tool to automate EPR experiments and even develop new ones. A software package, ESR-POISE, was released to allow EPR users with commercial spectrometers to access such methods. Finally, the construction of a spectrometer which can conduct magnetic resonance at unconventionally small scales thanks to quantum sensors (NV centres) is detailed. After describing design choices for the different elements of the instrument, a focus is made on the static magnetic field with Finite Element Analysis