Zeeman precession frequency

The third field region observed in the MARY curve shows a reversion of the field effect relative to the Zeeman effect saturation. We saw previously that the rate of S-Tq mixing depends on the difference in Larmor precession frequencies of the two radicals and that this difference may arise from a difference in the g-values of the radicals. This frequency difference is proportional to the strength of the applied field. As the g-value... 

A normal Zeeman effect can be explained within the framework of classical physics. Displacement of both the energy levels and the spectral line (7.7.7) corresponds to the Larmor precession frequency (refer to eq. (5.2.19))... 

Fig, 2.30a-d. Precession of a magnetic dipole in a homogeneous magnetic field Bq (a) Incoherent precession of the different dipoles (b) Synchronization of dipoles by a radio frequency (RF) field (c) Coherent superposition of two Zeeman sublevels (d) as the quantum-mechanical equivalent to the classical picture (c)... 

When an additional radio frequency field B = B o cos cot is added with B Bq, the dipoles are forced to precess synchroneously with the RF field B in the x-y-plane if co = (ol. This results in a macroscopic magnetic moment M = Nfi, which rotates with col in the x-y-plane and has a phase angle n/2 against B (Fig. 2.30c). The precession of the atoms becomes coherent through their coupling to the RF field. In the quantum-mechanical description, the RF field induces transitions between the Zeeman sublevels (Fig. 2.30d). If the RF field B is sufficiently intense, the atoms are in a coherent superposition of the wave functions of both Zeeman levels. 

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