Nuclear induction

At resonance, the magnetization vector M precesses about the vector B, i of the alternating field according to eq. (1.34). As a result, a component of transverse magnetization My.j rotates in the x y plane at the Larmor frequency v0. If a receiver coil is placed in the x y plane, the rotating magnetic vector Myj induces an electromotive force measurable as an inductance current. This process is called nuclear induction [5, 8]. The orientation of the coil axis will affect the phase relative to B1 i but not the magnitude of the induction current. 

In the rotating frame of reference, the field vector i of the rf field, rotating at angular 

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The January and February 1946 issues of the scientific journal Physical Reviews featured two independent research reports by Felix Bloch of Stanford and Edward Purcell of Harvard. The articles, The Nuclear Induction Experiment and Resonance Absorption by Nuclear Magnetic Moments in a Sohd, weren t bedtime reading. They described work that would seem to be... 

In the conventional NMR experiment, a radio-frequency field is applied continuously to a sample in a magnetic field. The radio-frequency power must be kept low to avoid saturation. An NMR spectrum is obtained by sweeping the rf field through the range of Larmor frequencies of the observed nucleus. The nuclear induction current (Section 1.8.1) is amplified and recorded as a function of frequency. This method, which yields the frequency domain spectrum f(ai), is known as the steady-state absorption or continuous wave (CW) NMR spectroscopy [1-3]. 

Pines, A., Gibby, M. G., and Waugh, J. A. (1972). Proton-enhanced nuclear induction spectroscopy. A method for high sesolution NMR of dilute spins in sohds. J. Chem. Phys. 56, 1776-1777. 

The solid state high resolution n.m.r. spectra were run on a CXP 200 BruKer spectrometer in which the 31P nucleus resonates at 81 MHz. Samples used were finely powedered and hand-tamped in glass tubes. The spectra were recorded using the Proton Enhanced Nuclear Induction Technique (6) on the same basis of a one shot cross polarization and high power decoupling during acquisition. A capillary tube of trimethylphosphate inserted in the powder sample is used as internal reference. 

Bjerve, K.S. (1973). The Ca2+-dependent biosynthesis of lecithin, phosphatidylethanolamine and phosphatidylserine in rat liver subcellular particles. Biochim. Biophys. Acta 296,549-562. Bloch, F., Hansen, W.W., Packard, M. (1946). Nuclear induction. Phys. Rev. 69,127. Borkenhagen, L.F., Kennedy, E.P., Fielding, L. (1961). Enzymatic formation and decarboxylation of phosphatidylserine. J. Biol. Chem. 236, PC28-PC30. 

Bloch F, Hansen WW, Packard ME. 1946. Nuclear induction. Phys Rev 69 127. 

The Bloch equations can be solved analytically under the condition of slow passage, for which the time derivatives of Eq. 2.48 are assumed to be zero to create a steady state. The nuclear induction can be shown to consist of two components, absorption, which is 90° out of phase with B, and has a Lorentzian line shape, and dispersion, which is in phase with B,. The shapes of these signals are shown in Fig. 2.10. By appropriate electronic means (see Section 3.3), we can select either of these two signals, usually the absorption mode. 

J. T. Arnold, S. S. Dharmatti, and M. E. Packard, Chemical Effects on Nuclear Induction Signals from Organic Compounds, /. Chem. Phys. 19 (1951), 507. 

Lippmaa et al. (86) have successfully studied solid state Si NMR of several trimethylsilyl silicate samples using proton-enhanced nuclear induction spectroscopy and magic angle spinning. They showed that the high resolution Si NMR of solids can be useful for structural studies of certain soluble and insoluble silicates, because many of these compounds with well defined molecular structures in the solid state tend to undergo very complicated rearrangements and condensation in solution. (93)... 

AS amplitude of ee nuclear induction A Pc suction pressure of capillaries... 

Fig. 12. Dependence of free nuclear induction amplitude Aq and volume content of unfrozen water w on temperature for phenolic foams of various apparent density a 1, a 2, o 3, 4 (the figures denote the samples listed in Table 6)...

Saha AK Das TP (1957)Theory and applications of nuclear induction. Saha Institute of Nuclear Physics, Calcutta, India... 

Fig. 1. Oscillograph trace of the nuclear induction signal from ethyl alcohol. The peaks from left to right represent OH, CH2, and CH, (from ref. 3). Reproduced with permission from the American Institute of Physics.

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