Oxygen is one of the most ubiquitous elements in chemistry and materials science, yet one of the most elusive elements for spectroscopic investigation by solid-state Nuclear Magnetic Resonance (SSNMR). Used to determine the structure of materials and chemicals on the atomic scale, SSNMR requires nuclei that have magnetic moments. Yet, less than four of every 10,000 oxygen nuclei are 17O, the only NMR-active isotope of oxygen. Detecting the elusive oxygen isotope now has become a reality thanks to unprecedented advancement in SSNMR, referred to as Dynamic Nuclear Polarization (DNP). Most recently, researchers have demonstrated new measurements that extend DNP-based 17O SSNMR well beyond its current capabilities. The technique transfers the DNP-enhanced hydrogen (1H) magnetization to 17O nuclei using the so-called PRESTO scheme, thereby reducing the experimental time by a factor of 25 compared to the previously used cross-polarization. This has led to the first detection of 17O sites on the surface of silica, measurements of 1H-17O distances and two-dimensional 1H-17O correlation spectra, used for analysis. These developments in enhanced sensitivity may facilitate new widespread investigations of the structure and dynamics in a variety of oxygen-containing materials including catalysts and nanoparticles.
Natural Abundance 17O DNP Two-Dimensional and Surface Enhanced NMR Spectroscopy