Physical Chemistry: Abstracts 501-561

In NuclearMagnetic Resonance (NMR), measurements of transverserelaxationt imes T 2 of protons are challengingd ue to modulations arising from homonuclear J-couplings.The suppression of thesee chom odulations in time domaini sacounterpart to thed ecouplingo fm ultiplets in frequency domain.We compare differenttechniquestocircumventthisproblem:-S pin-lock sequences to measure T 1ρ -C arr-Purcell-Meiboom-Gill (CPMG) echot rains with moderater adiofrequency(rf)pulses[1] -P erfect Echoestorefocus homonuclear J-couplings [2,3]Allt echniquesc an suppresse chom odulations andl ead to exponentiald ecays,b ut thea pparent transverser elaxationt imes T 2 are not always identical.T his depends on whetherap ulse sequencei srefocusing or locking the homonuclear J-couplings.While acontinuous-wave rf-fieldc an lock theinphase magnetization I x , refocusing maya llowapartialc onversioni nto antiphase magnetization2I y S z .The relaxationtimes of thesetwo coherences are usuallynot identical andthe antiphase magnetizationdecays faster.

Abstract licence: CC BY-NC

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