Phase modulation in dipolar-coupled A₂ spin systems: effect of maximum state mixing in ¹H NMR in vivo

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• 作者：Schr脙脙der ; Leif ; Schmitz ; Christian ; Bachert ; Peter
• 关键词：Phase modulation ; Dipolar A₂ system ; Creatine(phosphate) ; Residual dipolar coupling ; Muscle tissue
• 刊名：Journal of Magnetic Resonance
• 出版年：2004
• 期刊代码：126_10907807
• 类别：ch
• 出版时间：December, 2004
• 卷：171
• 期：2
• 页码：207-212
• 文件大小：325 K

摘要

Coupling constants of nuclear spin systems can be determined from phase modulation of multiplet resonances. Strongly coupled systems such as citrate in prostatic tissue exhibit a more complex modulation than AX connectivities, because of substantial mixing of quantum states. An extreme limit is the coupling of n isochronous spins (A_n system). It is observable only for directly connected spins like the methylene protons of creatine and phosphocreatine which experience residual dipolar coupling in intact muscle tissue in vivo. We will demonstrate that phase modulation of this 芒芒芒pseudo-strong芒芒芒 system is quite simple compared to those of AB systems. Theory predicts that the spin-echo experiment yields conditions as in the case of weak interactions, in particular, the phase modulation depends linearly on the line splitting and the echo time.