Orientation of nuclear spins

Figure 6.76 Orientation of nuclear spins in the presence of a magnetic field, and the resulting net magnetization vector (NMV) from excess low-energy spins aligned parallel to field. Adapted from C. Westbrook and C. Kaur, MRI in Practice, 2nd ed., p. 6. Copyright 1998 by Blackwell Science Ltd.

FIGURE 5.1 Schematic representation of the origin of electron-coupled spin-spin interaction. Nuclear spins are denoted by boldface arrows, electron spins by lightface arrows, (a) Antiparallel orientation of nuclear spins (b) parallel orientation of nuclear spins. 

Nuclear magnetic resonance NMR Quantized orientation of nuclear spin in a magnetic field. Energy separations sampled with radiofrequency radiation. Identification of histidine by deuterium exchange (N—H vs. N—D) at or near metal, especially if paramagnetic. 

Fig. 1. (a) Energy levels diagram and allowed transitions of an ensemble of spins with I = 1/2 in the absence and the presence of Bo- The small arrows indicate the orientation of nuclear spins relative to Bo- (b) Energy diagram and allowed single-quantum transitions for spins with / = 1. 

Orientation of Nuclear Spins in an Applied Magnetic Field... 

Consider an unpaired electron on a hydrogen atom, which has a nuclear spin I =. The nucleus (a single proton) has two possible orientations of its spin, labeled by ntj = + j and mj = —Each orientation of nuclear spin will interact, or couple, with the unpaired electron in such a way that the local magnetic field experienced by the electron is slightly different The magnitude of this difference is represented by a hyperfine coupling constant a, such that... 

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