Time-dependent Effects in Magnetic Resonance
We have already come across the fact that the trace of a magnetic resonance spectrum consists of a series of peaks each having some more or less well-defined shape. Even where there is only one line, it is clear that absorption takes place over a range of frequencies for a given applied field, and this can be ascribed to the fact that the field acting on an individual spin is modified by its immediate environment, so that different spins experience different instantaneous fields. In solutions, these local fields are fluctuating rapidly due to Brownian movement, i.e. molecules in the liquid are vibrating, rotating and moving about rapidly and at random. In the following discussion we shall use the word “spin” for the moment of the particular nuclear-type or odd electron whose resonance is being observed.
KeywordsNuclear Spin Electric Field Gradient Dynamic Nuclear Polarization Hydroxyl Proton Chemically Induce Dynamic Nuclear Polarization
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