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1. Fast high-resolution J-resolved correlation spectroscopy in inhomogeneous fields | |||
CHEN Hao,ZHANG Zhiyong,CAI Shuhui,CHEN Zhong | |||
Physics 25 October 2014 | |||
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Abstract:Multi-dimensional NMR spectroscopy alleviates the jam or even overlaps of peaks in one-dimensional spectra of complicated samples, extending the application of NMR spectroscopy. However, the acquisition of high-resolution NMR spectra relies on high homogeneity of magnetic field, which is difficult to achieve in many cases. In this study, we present a fast NMR approach for acquiring high-resolution 3D spectrum in inhomogeneous fields via intermolecular zero-quantum coherence and spatial encoding technique, providing J-resolved spectrum and correlation spectrum information simultaneously within the acquisition time scale for a conventional two-dimensional spectrum. | |||
TO cite this article:CHEN Hao,ZHANG Zhiyong,CAI Shuhui, et al. Fast high-resolution J-resolved correlation spectroscopy in inhomogeneous fields[OL].[25 October 2014] http://en.paper.edu.cn/en_releasepaper/content/4615284 |
2. Hadamard-encoded high-resolution NMR spectroscopy via intermolecular single-quantum coherences | |||
KE Hanping,CAI Honghao,CAI Shuhui,CHEN Hao,LIN Yanqin,CHEN Zhong | |||
Physics 07 October 2014 | |||
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Abstract:NMR spectroscopy plays an important role in metabolite studies because it can provide atomic level information critical for understanding biological systems. Nevertheless, NMR investigations on biological tissues are hampered by the magnetic field inhomogeneities originating from variations in macroscopic magnetic susceptibility, which lead to broad spectral lines and subsequently obscure metabolite signals. A new pulse sequence based on intermolecular single-quantum coherences was proposed to obtain one-dimensional high-resolution NMR spectra in inhomogeneous magnetic fields via Hadamard encoding. The new method can provide resolution-improved spectra directly through one-dimensional acquisition within a relatively short acquisition time. Theoretical derivation was performed and the conclusion was tested by solution samples in purposely de-shimmed magnetic fields and pig brain tissue sample. The experimental results show that this sequence can yield useful structural information, even when the field inhomogeneity is sufficiently severe to erase almost all spectral information with conventional one-dimensional single-quantum coherence techniques. Moreover, good solvent suppression efficiency can be achieved by this sequence. This sequence may provide a promising way for high-resolution NMR spectroscopy of biological tissue. | |||
TO cite this article:KE Hanping,CAI Honghao,CAI Shuhui, et al. Hadamard-encoded high-resolution NMR spectroscopy via intermolecular single-quantum coherences[OL].[ 7 October 2014] http://en.paper.edu.cn/en_releasepaper/content/4612484 |
3. Observation of intermolecular double-quantum coherence signal dips in nuclear magnetic resonance | |||
Shen Guiping,Cai Congbo,Cai Shuhui,Chen Zhong | |||
Physics 05 April 2011 | |||
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Abstract:The correlated spectroscopy revamped with asymmetric Z-gradient echo detection sequence was modified to investigate intermolecular double-quantum coherence nuclear magnetic resonance signal dips in highly polarized spin systems. It is found that the occurrence of intermolecular double-quantum coherence signal dips is related to the sample geometry, field inhomogeneity and dipolar correlation distance. If the field inhomogeneity is refocused, the signal dip occurs at a fixed position whenever the dipolar correlation distance approaches the sample dimension. However, the position is shifted when field inhomogeneity exists. Experiments and simulations were performed to validate our theoretic analysis. These signal features may offer a unique way to investigate porous structures and may find applications in biomedicine and materials science. | |||
TO cite this article:Shen Guiping,Cai Congbo,Cai Shuhui, et al. Observation of intermolecular double-quantum coherence signal dips in nuclear magnetic resonance[OL].[ 5 April 2011] http://en.paper.edu.cn/en_releasepaper/content/4420309 |
4. Detection and characterization of intermolecular multiple-quantum coherence NMR signal of IS (I=1/2, S=3/2) spin systems | |||
Zhang Wen,Chen Song,Cai Shuhui,Chen Zhong | |||
Physics 15 December 2010 | |||
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Abstract:Intermolecular multiple-quantum coherences (iMQCs) have some intrinsic properties different from conventional single-quantum coherences in solution NMR. In this paper, we extended our study to heteronuclear iMQCs in IS (I=1/2, S=3/2) spin systems. A sample of sodium chloride (NaCl) water solution was taken as an example. Heteronuclear multiple-quantum Correlated Revamped by Asymmetric Z-gradient Echo Detection (CRAZED) experiments were performed. One- and two-dimensional heteronuclear iMQC spectra were obtained. The quantum-mechanical treatment was used to deduce the signal expressions. Magical angle experiments validate that the signals are indeed from intermolecular dipolar interaction and insensitive to the imperfection of radio-frequency (RF) flip angles. Both experimental results and theoretical analysis indicate that heteronuclear CRAZED experiment allows coherence transfer from spin-3/2 nuclei to spin-1/2, and vice verse. Furthermore, the dependences of iMQC signal intensities on RF pulse flip angles follow the same rules as those for heteronuclear IS (I=1/2, S=1/2 or 1) spin systems. | |||
TO cite this article:Zhang Wen,Chen Song,Cai Shuhui, et al. Detection and characterization of intermolecular multiple-quantum coherence NMR signal of IS (I=1/2, S=3/2) spin systems[OL].[15 December 2010] http://en.paper.edu.cn/en_releasepaper/content/4398006 |
5. Harmonic peaks in 1D NMR spectra induced by radiation damping fields | |||
Ling Peng,Shuhui Cai,Riqiang Fu,Chaohui Ye,Zhong Chen | |||
Physics 04 August 2009 | |||
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Abstract:It is found experimentally that there exist some harmonic peaks in one-dimensional NMR spectra of solution samples with two dominant solvents. Theoretical analysis indicates that such harmonic peaks are resulted from the interaction between two radiation damping fields induced by the dominant solvents. Using a homo-nuclear decoupling pulse as a radiation damping field, a novel detection approach is proposed to investigate the harmonic peaks without interferences caused by the nonlinear amplification of the receiver. The results presented herein give a new insight into the radiation damping effects in samples with solvent mixtures (e.g., natural products) at high fields. | |||
TO cite this article:Ling Peng,Shuhui Cai,Riqiang Fu, et al. Harmonic peaks in 1D NMR spectra induced by radiation damping fields[OL].[ 4 August 2009] http://en.paper.edu.cn/en_releasepaper/content/34265 |
6. High-resolution NMR spectra in inhomogeneous and unstable fields via three-pulse method | |||
Ling Peng,Zhenyao Zheng,Zhenmin Zhang,Shuhui Cai,Zhong Chen | |||
Physics 04 August 2009 | |||
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Abstract:In modern solution nuclear magnetic resonance (NMR), the spectral resolution is closely related to the spatial homogeneity and temporal stability of the magnetic field. The spectral linewidths are usually proportional to the overall field homogeneity and stability experienced by the sample. Recently, many high-resolution NMR methods have been developed, but few of them are applicable in inhomogeneous and unstable fields. In this paper, a high-resolution three-pulse method based on intermolecular zero-quantum coherences (iZQCs) was proposed. This method is insensitive to field inhomogeneity and unstability, so the spectral information such as chemical shift can be retained in the resulting spectra. Compared to the CPMG-HOMOGENIZED method, this method can give almost pure iZQC signals. | |||
TO cite this article:Ling Peng,Zhenyao Zheng,Zhenmin Zhang, et al. High-resolution NMR spectra in inhomogeneous and unstable fields via three-pulse method[OL].[ 4 August 2009] http://en.paper.edu.cn/en_releasepaper/content/34255 |
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