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首页> 外文期刊>The Open Magnetic Resonance Journal >A Method to Selectively Observe a Desired Linear Combination of Chemical Shifts in GFT Projection NMR Spectroscopy
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A Method to Selectively Observe a Desired Linear Combination of Chemical Shifts in GFT Projection NMR Spectroscopy

机译：一种在GFT投影NMR光谱中选择性观察所需化学位移线性组合的方法

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In recent years, several new methods have emerged for rapid NMR data collection. One class of methods isprojection NMR spectroscopy, which involves phase sensitive joint sampling of two or more chemical shifts in an indirectdimension of a multidimensional NMR experiment. In the current implementations of this method, cosine/sine modulationof all chemical shifts involved in the joint sampling are collected and stored as separate FIDs. A post-acquisition dataprocessing step (application of G-matrix) then separates the different inter-modulations of chemical shifts. Thus, jointsampling of K+1 spins results in 2K combination of chemical shifts (also representing 2K projection angles). One limitationof this approach is that even if only a few of the 2K components of the multiplet (or projection angles) is desired, an entiredata set containing information for all 2K shift combinations is collected. We propose here a simple method which releasesthis restriction and allows one to selectively detect only the desired linear combination of chemical shifts/projection anglesout of 2K combinations in a phase sensitive manner. The method involves selecting the appropriate cosine/sine modulationsof chemical shifts and forming the desired linear combination by phase cycling of the radiofrequency pulses andreceiver. This will benefit applications where only certain linear combination of shifts are desired or/and are sufficient.Further, G-matrix transformation required for forming the linear combination is performed within the pulse sequence.This avoids the need for any post-acquisition data processing. Taken together, this mode of data acquisition will fosternew applications in projection NMR spectroscopy for rapid resonance assignment and structure determination.
机译：近年来，出现了一些新的快速NMR数据收集方法。一类方法是投影NMR光谱法，它涉及在多维NMR实验的间接维度中对两个或多个化学位移的相敏感联合采样。在此方法的当前实现中，将收集联合采样中涉及的所有化学位移的余弦/正弦调制，并将其存储为单独的FID。然后，获取后的数据处理步骤（应用G-矩阵）将化学位移的不同互调分开。因此，K + 1自旋的联合采样导致化学位移的2K组合（也代表2K投影角）。这种方法的局限性在于，即使只需要多重峰的2K分量中的几个（或投影角），也要收集包含所有2K位移组合信息的整个数据集。我们在这里提出一种简单的方法，该方法解除了这种限制，并且允许以相敏方式仅选择性地检测2K组合中化学位移/投影角的所需线性组合。该方法包括选择适当的化学位移的余弦/正弦调制，并通过射频脉冲和接收器的相位循环形成所需的线性组合。这将有利于仅需要或仅需要某些线性移位组合的应用。此外，在脉冲序列内执行形成线性组合所需的G矩阵变换，从而避免了任何采集后数据处理的需求。综上所述，这种数据采集方式将促进投影NMR光谱在快速共振分配和结构确定中的新应用。

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