Spin lock power levels

RF POWER LEVELS FOR SHAPED PULSES AND SPIN LOCKS... 

The ROESY used to be a bit difficult to set up because the low power spin-lock RF had to come from a different source than the hard pulse RF. Now rapid solid-state power switching is so routine that all H RF comes from the same source, with no variation of phase or frequency. ROESY tends to replace the NOESY experiment for NOE measurements, especially for small molecules where T2 is relatively long. Because the NOE builds up about twice as fast in the x -y plane as it does on the z axis, ROESY mixing times are set to about half of what would be the NOESY mixing time. There is one additional parameter to set up the power level ( Z i field strength ) of the spin lock pulse. This is typically... 

Note that after spin-locking the protons, the proton transmitter is simply left on. During the times that the carbon transmitter is on, the two rf fields satisfy the Hartmann-Hahn condition and the two different kinds of spin reservoirs are in thermal contact as described earlier. When the carbon transmitter is off, the carbon FID s are being recorded and the proton transmitter must be left on so that it can perform as a decoupler. [The amplitude of the spin-locking "pulse" is reduced compared to the initial n/2 pulse in order to keep the transmitter power level at a reasonable value. ]... 

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