ARTIFACTS IN GRADIENT ENHANCED HSQC

梯度增强的异核单量子关联 (GEHSQC)实验被广泛应用，特别是作为构建 多维核磁共振，例如在3D NOESY HSQC实验中。 然而，仔细检查GEHSQC光谱发现了大量的 小型文物。在高动态范围的情况下，这些伪像 可能会干扰光谱解释，因为这些伪像 与强烈的信号相关联可能会模糊弱相关性 利息。我们试图解释这些文物的起源，并 找到一种方法来抑制它们。它们被证明是由 回传过程中质子标量耦合的演化 通过中继相干传输机制对脉冲序列进行编码。这个 人造物看起来像是涉及遥远质子的交叉峰。产品 伪影形成的算子分析及实验结果 证明这些人工产物的大小可以超过10% 主峰。因此，这些文物代表了一个重要的 敏感度下降。

The Gradient Enhanced Heteronuclear Single Quantum Correlation (GEHSQC) experiment is widely used, especially as a building block in multi-dimensional NMR, for instance in 3D NOESY HSQC experiments. However, close inspection of GEHSQC spectra reveals a large number of small artifacts. In situations of high dynamic range, these artifacts can interfere with spectral interpretation, since the artifacts associated with intense signals can obscure weak correlations of interest. We have sought to explain the origin of these artifacts and find a method to suppress them. They turn out to be caused by the evolution of proton scalar coupling during the back-transfer portion of the pulse sequence via a relayed coherence transfer mechanism. The artifacts appear as cross-peaks involving remote protons. Product operator analysis of artifact formation and experimental results demonstrate that the magnitude of these artifacts can exceed 10% of the main peak. Therefore, these artifacts represent a significant loss in sensitivity.