I can understand why a non-specific 180 degree refocusing pulse shouldn't refocus J-coupling.
I also, think I understand, how repetitive selective pulses can decouple a system - e.g. an AX system by repetitively inverting the X spin so that the A spin feels an average.
How is scalar coupling inlvolved in the mechanism of T2 prolongation of fat in MRI using multiple echo sequences? My understanding is that these pulses are non-specific and hence shouldn't cause much decoupling - yet the prolongation of T2 is quite significant.
What's going on? Any one know? Any good pointers?
I also, think I understand, how repetitive selective pulses can decouple a system - e.g. an AX system by repetitively inverting the X spin so that the A spin feels an average.
How is scalar coupling inlvolved in the mechanism of T2 prolongation of fat in MRI using multiple echo sequences? My understanding is that these pulses are non-specific and hence shouldn't cause much decoupling - yet the prolongation of T2 is quite significant.
What's going on? Any one know? Any good pointers?
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