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The conversion of heteronuclear MQC to SQC is accomplished reversing the steps described in heteronuclear Multiple Quantum Coherences (MQCs). This block is found as the final step in the HMQC experiment.REQUIREMENTS
The process follows as:
- The initial starting state is 1H-X MQC in the form (IxSy).
- A 90º X pulse creates antiphase 1H SQCs (IxSz). At this moment, the 1H signal could be detected without X decoupling.
- A period optimized to 1/2*1JXH to allow evolution of heteronuclear coupling constants. Simultaneous 180º 1H and X pulses could be applied at the middle of this period to refocus 1H chemical shift evolution. The final result is in-phase 1H magnetization (Iy) that can be detected with optional X decoupling.
Easy implementation on AVANCE spectrometers.EXPERIMENTAL DETAILS
For further details about implementation of HMQC experiments in AVANCE spectrometers see, for instance, Tutorial: 2D HMQC experimentSYNTAX
The standard way to implement a SQC-from-MQC block in a pulse program is:RELATED TOPICSin which:
...
(p3 ph1):f2
d2
...
- d2 is the refocusing period to be optimized to 1/(2*JXH).
- p3 is the 90º 13C pulse (in microseconds) applied at a power level pl2 from the channel f2.
- The phase may be specified at the end of pulse program.