Clean in-phase layer selection in-core selective coherence spectrum method

Abstract

The invention provides a clean in-phase layer selection in-core selective coherence spectrum method. A modified perfect echo module is used for achieving coherent transfer between the same phases, unwanted signals are removed in combination with selective pulses and phase removing gradients, only J coupling modulation signals generated when t1 and t2 are modulated by cosine functions of an excitation core and an observation core are finally reserved, and the signal strength is affected by a delta value. The two-dimensional J coupling modulation of the excitation core and the observation core presents an in-phase square in a spectrogram, the coupling information of the observation core and other cores is embodied on the lateral offset of the square, and the coupling information of the excitation core and other cores is embodied on the longitudinal offset of the square at present, and the modulation causing transverse and longitudinal offset is cosine modulation, so that the property that the spectral peak is in-phase is not influenced.

Description

technical field [0001] The invention relates to a nuclear magnetic resonance method, in particular to a nuclear magnetic resonance method with clean and homogeneous layer-selective homonuclear selective coherence spectrum. Background technique [0002] NMR spectroscopy is a powerful analytical tool with a wide range of applications. J-coupling is an important parameter in NMR spectroscopy, which can provide valuable information about molecular structure and conformation. Among them, two-dimensional correlation spectroscopy (“COSY”) experiments that provide molecular J-coupling relationships play an indispensable role in molecular resolution, but their numerical resolution has been low due to the limited number of sampling points in the indirect dimension. Numerical resolution can be improved by a selective ("soft") COZY method, which facilitates the analysis of the coupling constant between a given proton and its coupled pair. However, since the final signal is composed of...

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Problems solved by technology

However, since the final signal is composed of the in-phase component and the anti-phase component, when the positive and negative signals are close to each other, the resulting self-cancellation makes spectrogram analysis difficult

In addition, the "soft" COZY experiment with non-parallel sampling can only measure the coupling relationship between one excited nucleus and one observed nucleus at a time, which will consume double the experimental time when measuring all the coupling situations of a given proton in the sample

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