https://doi.org/10.1351/goldbook.08374
Frequency shift in the nuclear magnetic resonance spectrum of a paramagnetic species that refers to the relative shift \(\boldsymbol{K}\) in NMR frequency for atoms in a metal (e.g., sodium) compared with the same atoms in a nonmetallic environment (e.g., as a salt).
Note: The observed shift reflects the local magnetic field produced at the metal nucleus by the magnetization of the conduction electrons.