Brooklyn College, Department of Physics, 2900 Bedford Avenue, Brooklyn, NY 11210, United States.
J Magn Reson. 2010 Jul;205(1):102-8. doi: 10.1016/j.jmr.2010.04.008. Epub 2010 Apr 24.
We report on the results of a simulation based study of the effect of various experimental artifacts for spin I=1 double quantum filtered NMR. The simulation captures the effects of static field inhomogeneity, finite pulse widths, phase errors, transients and radio frequency field inhomogeneity. We simulated the spectral distortions introduced under these errors for four, eight and sixteen step phase cycles that are well known in the NMR community. The dominating pulse errors are radio frequency field inhomogeneity and antisymmetric pulse transients. These errors result in the reduction of signal intensity as well as an introduction of distortions in the detected double quantum filtered spectrum. Using the simulation tool we studied the improvement one obtains when implementing a sixteen step phase cycle over a four step phase cycle. The results indicate that implementing a sixteen step phase cycle over an eight or four step phase cycle does not result in a significant reduction in the DQF intensity loss, or reduction in spectral distortions for antisymmetric transients.
我们报告了基于模拟的自旋 I=1 双量子滤波 NMR 实验伪影影响的研究结果。该模拟捕获了静态磁场不均匀性、有限脉冲宽度、相位误差、瞬变和射频场不均匀性的影响。我们模拟了在这些误差下,对于在 NMR 领域广为人知的四个、八个和十六个相循环步骤引入的光谱失真。主要的脉冲误差是射频场不均匀性和非对称脉冲瞬变。这些误差会导致信号强度降低,以及检测到的双量子滤波光谱出现失真。我们使用仿真工具研究了当在四步相循环中实现十六步相循环时可以获得的改善。结果表明,在八步或四步相循环中实现十六步相循环不会导致 DQF 强度损失显著降低,或者非对称瞬变引起的光谱失真减少。