Indirect and direct ~(29)Si dynamic nuclear polarization of dispersed nanoparticles

摘要

We show how the ~(29)Si NMR signals of dispersed inorganic nano-particles of laponite~® can be enhanced by Dynamic Nuclear Polarization (DNP). The direct DNP enhances the signals of ~(29)Si nuclei near unpaired electrons, whereas the indirect DNP via ~1H enhances the signals of more remote sites. As a local and non-destructive technique, solid-state nuclear magnetic resonance (NMR) provides precious insight into the atomic-scale structure and dynamics of nanoparticles (NPs), i.e. materials with three external dimensions sized between 1 and 100 nm.Nevertheless, the low sensitivity of NMR can preclude the observation of diluted species, such as the edge, corner, grafting or surface sites. The sensitivity limitation of NMR is even more acute for nuclei with long longitudinal relaxation times (T_(1n), low natural abundance and/or low gyromagnetic ratio, such as ~(29)Si.