A novel low-E field coil to minimize heating of biological samples in solid-state multinuclear NMR experiments

Resonator with reduced sample heating and increased homogeneity for solid-state NMR

“…Traditionally the chemical shift of the hydroxyl protons relative to the ethyl protons in ethylene glycol found widespread application [40][41][42]. In recent publications also lanthanide compounds [12,43] or bicelles [13] were used to monitor temperature increase due to rf heating in NMR samples.…”

“…For the characterization of the temperature increase as function of the applied B 1 field, we used an rf pulse sequences for heating experiments proposed by several authors [12,13,16] as illustrated in Fig. 9a.…”

“…For solid-state magic-angle-spinning NMR, where solenoidal coils are widely used, the appearance of high NMR frequencies may lead to a degradation of rf homogeneity and an increase of fringe electric fields in the sample volume that may interact with the bulk electric properties of the sample [1][2][3][4][5][6][7][8][9][10][12][13][14][15][16].…”

“…Some alternative ''single-coil'' [12][13][14]17] or ''cross-coil'' [15,16,18,19] geometries have been proposed that exhibit reduced rf electric fields inside the sample volume. Here single-coil geometry means that the coil exhibits, as for a straightforward solenoidal coil, just two coil ports and that it is compatible with the probe rf circuitry used for solenoidal coils.…”

Optimizing ssNMR experiments for dilute proteins in heterogeneous mixtures at high magnetic fields

“…More recently, the so-called Z-coil configuration has been proposed that employs a 1/2 turn central portion and pancake coils at each end. 52 The Z-coil appears to reduce heating, but also has lower intrinsic efficiency than simple wire solenoids. However, although both of these approaches keep the electric fields associated with coil self-resonance away from the sample, neither of them particularly mitigates the selfresonance itself.…”