HIGH-FIELD DNP / EPR LABORATORY

Measurements of high-field EPR and DNP. Ultra-wideline NMR spectroscopy is one of the toughest areas of solid-state NMR. The ultra-wide (> 0.5 MHz) NMR spectra, while potentially containing a wealth of important chemical information, present unique challenges to the NMR spectroscopist, notably low signal intensity and bandwidth limitations. In this project we explore novel methods to utilize our unique spectrometer for the efficient hyperpolarization of those demanding systems and for their structural characterization.

Design and build-up of a unique high-field EPR/DNP spectrometer. Our group constantly develops new experiments and adapts our hardware according to the experimental needs. A typical DNP experiment is performed at cryogenic temperature, and requires simultaneous excitation and detection at sub-THz radiation (electron spins) and MHz radiation (nuclear spins). This requires in-house development of both mechanical and electronic hardware.

Quantum mechanical simulations to analyze and guide the experiments. The dynamics of electron and nuclear spins are governed by quantum mechanics. An in depth understanding of the different quantum mechanical processes driving DNP is required for the maximization of the method’s benefits. Hyperpolarization of ultra-wideline nuclei presents complex theoretical challenges associated with the unusual magnitude of the anisotropic nuclear spin interactions, typically ignored in traditional theoretical treatments. The goal of this project is to develop the modelling and simulations framework for ultra-wideline DNP for data interpretation and guidance of future experiments.

Optimization of sample preparation for efficient DNP. The DNP sample composition plays a vital role in the achievable sensitivity and experimental reproducibility. A DNP sample consists of three components: The analyte from which we want to acquire the NMR spectrum; The polarizing agent – a radical that provides the electron spin to serve as polarization source; The matrix in which two former are embedded. The matrix is very important for optimal polarization transfer. A bad matrix will serve as a “polarization sink” preventing polarization from reaching the analyte, while a good matrix will allow for efficient polarization transfer and prolonged relaxation times for both electron and nuclear spins. In our group we aim to design new matrices which will allow for efficient DNP at temperatures > 100 K for a large range of different samples.