The meaning of dipolar and Zeeman order

The concept of Zeeman order has already been discussed in terms of relaxation in III.A. If a sample containing nuclear spins is introduced into an external magnetic field Hq, no magnetization appears immediately. However, as the sample is allowed to soak in the field, a magnetization parallel to the applied field develops. This happens because the spins, originally equally divided between the two energy states, i.e., 

The concept of dipolar order is less obvious. Consider the following experiment A sample with a long T which has 

While Tp the Zeeman relaxation time, is sensitive to motions occurring at the Larmor speed in the large applied field, the dipolar relaxation time is sensitive to fluctuations occurring at the Larmor speed in the local field which is three to five orders of magnitude smaller. The former might be in the range of 5-300 MHz while the latter will be in the few kHz range. 

Provided that the system is in a high field Hq, and that no rf fields are applied on resonance, the dipolar ordered system and the Zeeman system are isolated from each other, the only connection being through the lattice. The dipolar 

Note that one could have transitions of a nucleus up one Zeeman level and another nucleus down one Zeeman level to maintain the magnetization while altering the dipolar order. Because the dipolar reservoir is usually isolated from the Zee-man reservoir, a system can be prepared so that its Zeeman spin temperature is different from its dipolar temperature 

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