Double quantum spin flip rate

Double quantum spin flip rate constant, Wj. The kinetic rate constant controiiing the simuitaneous change in both spin states for a two-spin system where both spin-id spins go from the a to the p state or from the a to the p state. 

For a two spin system, Wq is the rate constant for the zero quantum spin flip, Wi is the rate constant for the single quantum spin flip, and W2 is the rate constant for the double quantum spin flip. For short correlation times, the ratio ofWjWyWo is 1Ve. 

Rotational Overhauser effect spectroscopy, ROESY. Syn. CAMELSPIN experiment A 2-D NMR experiment similar to the 2-D NOESY experiment except that the ROESY experiment employs a spin-lock using the B, field of the applied RE, thus skirting the problem of the cancellation of the NOE cross peak when correlation times become long enough to reduce the rate constant for the dipolar doubl quantum spin flip. 

The dipolar relaxation mechanism is unique because the dipolar coupling interaction contains two spin terms involving mutual spin flips - zero quantum t J. J. t and double quantum J J < j j transitions. All other relaxation processes are limited to single spin interchange. While the decoupler is on, the spin population differences between the levels irradiated are equalized as the rate of energy input from the decoupler greatly exceeds the outflow by relaxation. In dipolar coupled systems, the availability of double and zero quantum relaxation pathways (cross-relaxation) produces non-Boltzmann spin populations in the energy levels of the observed nucleus. These perturbed populations are measured as the nuclear Overhauser effect (nOe) effect rj). The relationship is... 

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