CNRS, Chimie et Interdisciplinarité: Synthèse, Analyse, Modélisation (CEISAM), Université de Nantes, UMR 6230, B.P. 92208, 2 rue de la Houssinière, F-44322 Nantes Cedex 03, France.
Magn Reson Chem. 2011 Jun;49(6):307-13. doi: 10.1002/mrc.2746. Epub 2011 Mar 31.
Ultrafast 2D NMR allows the acquisition of a 2D spectrum in a single scan. However, even when the acquisition of ultrafast spectra is carried out under optimized conditions, the appearance and the sensitivity of 2D spectra are often not satisfactory compared with what one could expect from this promising methodology. This is due to limitations in terms of sensitivity, spectral width and resolution, and also to non-ideal lineshapes characterized by asymmetric sinc wiggles. Here, we identify the origin of these distortions by means of numerical simulations compared with experimental data. We then propose a processing approach to improve lineshapes while increasing the sensitivity of ultrafast experiments. The method consists in multiplying the Fourier transform of ultrafast echoes by an optimized apodization function. The principles of the method are described, and a variety of window functions are tested to determine optimum processing conditions. The approach is finally applied to ultrafast 2D spectra, leading to symmetric lineshapes with a sensitivity increased by a factor of 2.
超快二维 NMR 允许在单次扫描中采集二维谱。然而，即使在优化条件下采集超快谱，与人们对这种有前途的方法所期望的相比，二维谱的外观和灵敏度往往不尽如人意。这是由于灵敏度、谱宽和分辨率方面的限制，以及由非理想的不对称 sinc 摆动特征的线形状造成的。在这里，我们通过与实验数据的数值模拟来确定这些扭曲的起源。然后，我们提出了一种处理方法，以在提高超快实验灵敏度的同时改善线形状。该方法包括通过优化的频域窗函数对超快回波的傅里叶变换进行乘法运算。本文描述了该方法的原理，并测试了各种窗函数，以确定最佳处理条件。最后，该方法应用于超快二维谱，得到了具有两倍灵敏度的对称线形状。
