This Demonstration visualizes the dynamics in the process of magnetic resonance in which the macroscopic magnetization

of an ensemble of paramagnetic particles is exposed to the common action of a static magnetic field

and a weak magnetic field

(

) that rotates with a frequency ω around

. The motion of

is governed by the so-called
Bloch equations. The effect of

on

becomes most dramatic when the rotational frequency ω is equal to the Larmor free precession frequency

(i.e., detuning

).
Many interesting solutions are registered as bookmarks, which you can activate by clicking the small cross at the upper right corner. For example:
• The
free Larmor precession, which occurs for

, so that magnetization precesses around

at the Larmor frequency.
• The

-
pulse, for which

rotates at the Larmor frequency (
detuning = 0) and for which

is switched on for a time duration

, such that

. As a result the magnetization is flipped by

into the

-

plane.
• The

-
pulse, for which

rotates at the Larmor frequency (
detuning = 0) and for which

is switched on for a time duration

, such that

. As a result the magnetization is flipped by

to the

direction.
•
Magnetic resonance with relaxation, for which the magnetization reaches a steady state. You can play with the value of the frequency detuning

. If

or

, the effect of

is small and the steady state is close to the equilibrium magnetization along

. However, when

, the effect of

is important and the steady state is reached far from the

axis.
• A
diabatic following occurs for

, in which case the magnetization precesses rapidly around the magnetic field and therefore follows the direction of

adiabatically.