发明授权
US4701708A Polarization transfer by selective homonuclear technique for suppression of uncoupled spins in NMR spectroscopy 失效
通过选择性同核技术在NMR光谱学中抑制非偶联自旋的极化转移

Polarization transfer by selective homonuclear technique for suppression
of uncoupled spins in NMR spectroscopy
摘要:
A method of suppressing at least one undesired resonance response signal while facilitating reception of at least one other desired NMR response signal from a coupled spin resonance in NMR spectroscopy, utilizes a pair of alternating sequences of RF signal pulses, with each sequence having an initial .pi./2 RF pulse, followed by a .pi. RF signal pulse having a temporal midpoint at a time interval T after the temporal midpoint of the initial pulse (where T=n/4J, with n being an odd integer and J being the spin coupling constant of the hydrogen nuclei) and a final .pi. RF signal pulse with a temporal midpoint at twice the time interval T after the temporal midpoint of the first .pi. RF signal pulse in that sequence. Only one of the pair of sequences is provided with a polarization transfer narrowband .pi. RF signal pulse symmetrically disposed about a temporal midpoint located at substantially a time interval T after the first .pi. RF signal pulse of that sequence and substantially at a frequency removed from the resonance frequency of at least one undesired uncoupled spin resonance. Response signals are acquired within a gating period including a temporal point thereof occurring at a time interval T after the temporal midpoint of the final .pi. RF signal pulse. The pair of recovered sets of data are substracted from one another to obtain a final data set in which noncoupled spin resonance data is substantially cancelled but desired coupled spin resonance data is preserved.
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