Coherence Transfer Inept And Dept

Now we are ready to see something truly magical in NMR. With our toolbox of pulses and delays, and the more complex "plug in" units of spin echoes, we can make net magnetization "jump" from one nucleus to another across the "bridge" of a J coupling or an nuclear Over-hauser effect (NOE) interaction. This strategy allows us to enhance the sensitivity of many experiments by starting with XH, which has the highest equilibrium population difference, and moving its magnetization to less sensitive nuclei such as 13C. Later, we will see how we can correlate two related spins (actually we correlate their chemical shift positions in the spectrum) to demonstrate the nature (J or NOE) and intensity of the relationship. We will do this first with selective one-dimensional (1D) experiments and then with two-dimensional (2D) experiments. In both cases, the basis of the correlation is making the magnetization "jump" from one nucleus to another by the process of magnetization transfer. But first we need to understand very clearly what this material is that we work with in NMR: the net magnetization. A little bit of review will help.

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