Paramagnetic defects in nanodiamonds

A characteristic feature of nanodiamond (ND), as of most nano-objects in which the number of atoms on the surface and within interface layers is comparable to that in the bulk, is the pronounced effect of the surface on the structural and electronic properties of the material. This is why investigation of the differences in the structure and behavior of defects and impurities between the nano- and bulk diamond is attracting particular interest. Where are defects and impurities located in ND and how have they been formed? Can the specific effects originating from the nanoscale of carbon particles be revealed in ND? Answers to these questions can be derived from electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) measurements, which provide important information on crystalline and electronic-nuclear structure and magnetic properties of materials. This chapter outlines the physical basis underlying these techniques, with subsequent summing up of the results obtained with EPR and NMR in studies of nanodiamonds in the recent years.