Ultra low-field nuclear magnetic resonance of liquids confined in ferromagnetic and paramagnetic materials

摘要

A nuclear magnetic resonance (NMR) procedure is used to measure weak magnetic fields in the vicinity of dilute ferromagnetic and/or paramagnetic materials. By detecting H-1 Larmor precession in common solvents at extremely low frequencies (50Hz), the magnetic field produced by remanent magnetization of the material is measured by NMR to a precision of 1 nT. In one example, the technique is used to quantify the magnitude and direction of remanent magnetization in a common aluminum alloy. In another example, a H-1 NMR linewidth 1Hz is demonstrated for liquid decane (n-C10H22) embedded inside a mesoporous silica matrix, despite the high concentration of paramagnetic cobalt sites that produce magnetic susceptibility gradients in the system. Application to systems of industrial relevance is discussed.