Nuclear Magnetic Resonance and

Magnetic Resonance Imaging

A vector model showing possible orientations of the nuclear spin angular momentum vector and its projections along the z axis for the case I =3/2.

the nuclear magneton

Nuclear Magnetic Resonance and

Magnetic Resonance Imaging

Experimental arrangement for nuclear magnetic resonance. The radio- frequency magnetic field created by the coil surrounding the sample and provided by the variable-frequency oscillator is perpendicular to the constant magnetic field created by the electromagnet. When the nuclei in the sample meet the resonance condition, the nuclei absorb energy from the radio-frequency field of the coil; this absorption changes the characteristics of the circuit in which the coil is included. Most modern NMR spectrometers use superconducting magnets at fixed field strengths and operate at frequencies of approximately 200 MHz.