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Glenn Facey
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32 followers
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Optimizing the Signal-to-Noise-Ratio with Spin-Noise Probe Tuning
We have all been taught to tune our NMR probes to maximize the pulse power delivered to our sample (or minimize the reflected power back to the amplifier).  This prevents damage to the amplifiers and minimizes the duration of 90° pulses at fixed power level...

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Boron Isotope Effects in Fluorine NMR Spectra
In previous posts on this BLOG, examples of  1 H/ 2 H and 12 C/ 13 C isotope effects were discussed.  The figure below shows an example of a 10 B/ 11 B isotope effect observed in the 19 F NMR spectrum of tetrabutyl ammonium tetrafluorobarate. The spectrum ...

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Correcting NMR Spectra for Poor Shimming - Reference Deconvolution
The pleasingly symmetric and narrow Lorentzian resonances in a high resolution NMR spectrum are truly things of stunning beauty, appreciated by all NMR spectroscopists. Their majesty depends on the homogeneity of the NMR magnet around the sample. Inhomogene...

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Testing an MAS Spin Detection Device
Recently, I had a problem with an MAS probe which would no longer allow measurement of an MAS spinning frequency.  I thought it might be instructive to describe the device and the steps I took to solve the problem.  An MAS spin detection device includes an ...

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The Effect of the <sup>2</sup>H Lock on Environmental Instability
The 2 H lock of an NMR spectrometer continuously monitors the frequency of the 2 H resonance of a deuterated solvent used to prepare the NMR sample.  If the frequency of the 2 H resonance changes due to an environmental instability while the lock is engaged...

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HMBC vs. H2BC
NMR spectroscopy is an indispensable tool for assigning the structure of organic compounds.  One very useful method in the NMR toolbox is the H eteronuclear M ultiple B ond C orrelation (HMBC) experiment.  HMBC data are 1 H detected and provide a 2D correla...

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Improved <sup>1</sup>H Resolution with <sup>14</sup>N Decoupling
The J coupling between 13 C and quadrupolar nuclides can be resolved, for example, in the cases of the 13 C NMR spectra of deuterated compounds , some cobalt complexes and some tetraalkyl ammonium salts .  The ability to resolve the coupling depends on the ...

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PSYCHE to Evaluate <sup>1</sup>H-<sup>19</sup>F Coupling Constants
Even small molecules can yield very complex 1 H NMR spectra as the result of spin - spin coupling.  This is particularly true for small molecules that contain fluorine.  It can sometimes be challenging to determine which splittings are due to 1 H- 1 H coupl...

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Pure Shift <sup>1</sup>H NMR - PSYCHE
Much effort has been directed to obtain broadband 1 H decoupled 1 H NMR spectra .  The subject has been reviewed recently. 1   One technique used to obtain such spectra is the pseudo- 2D Zangger - Sterk method 2,3 based on a selective refocusing pulse appli...

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Exchange Effects in HSQC Spectra
The effects of chemical or dynamic exchange on NMR spectra are very well known.  Exchange is often studied by observing line shape changes as a function of temperature , by 2d EXSY , inversion transfer or saturation transfer methods.  Effects due to exchang...
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