On the Shift of the Nuclear Magnetic Resonance in Paramagnetic Solutions

The Effect of Bulk Magnetic Susceptibility on Solid State NMR Spectra of Paramagnetic Compounds

“…The RF field amplitude used for all the experiments was 50 -60 kHz for both 1 H and 13 C. As reported on europium acetate and sodium neodymium ethylenediaminetetraacetate (23), continuous-wave (CW) 1 H decoupling was found not to be effective to the lanthanide ethylsulfates because of the wide spread of 1 H resonance frequencies caused by the paramagnetic ions. The static 13 C NMR spectra of the lanthanide ethylsulfates were recorded under frequency-switched 1 H decoupling, whose frequency is switched every among three different 1 H offsets, Ϫf, 0, and f, while the phase and the amplitude are kept constant.…”

“…[2] has to be replaced by the sum of surface integrals. Equation [1] can be written in the following form:…”

“…Bulk magnetic susceptibility (BMS) of a sample produces a demagnetizing field and causes a shift of NMR resonance frequency (1,2). This shift depends on the shapes of interface where magnetic susceptibility changes discontinuously and on the distances between the observed nuclei and the interface.…”

“…The theoretical values were compared with 1 H NMR spectra of small molecules absorbed on a diamagnetic zeolite. These ABMS and BMS effects are expected to be more significant in paramagnetic samples.…”

Paramagnetic electrodes and bulk magnetic susceptibility effects in the in situ NMR studies of batteries: Application to Li1.08Mn1.92O4 spinels

“…The difficulties stem from the effect of the magnetic properties of the paramagnetic electrode material on the NMR spectra of the whole battery. A paramagnetic material can cause shifts and severe broadening of the NMR resonances via two possible mechanisms-the electron-nuclear hyperfine interaction [8] and the bulk magnetic susceptibility (BMS) [9,10], the effects being additive. The hyperfine or Fermi-contact mechanism, which results from electron-nuclear interactions that are mediated by the covalent bonds in the material, can result in significant shifts of the isotropic resonances, while the electron-nuclear dipolar coupling through-space interaction generally causes line-broadening.…”