Extending Timescales and Narrowing Linewidths in NMR
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The internuclear distance between two homonuclear dipolar-coupled dil. spins-1/2, SA and SX, can be measured by rotational resonance expts. in solid state NMR. These involve rotating the sample at the magic angle while fulfilling the condition for rotation ...
It is shown how amplitude-modulated radio-frequency pulses optimized for selective inversion of magnetization can be applied to static powder samples with inhomogeneously broadened spectra. Selective one-dimensional methods can in principle provide informa ...
Longitudinal nuclear magnetic relaxation in coupled two-spin systems is discussed in terms of magnetization transfer modes, a generalization of the magnetization modes commonly used in the discussion of one-dimensional NMR relaxation expts. The symmetry pr ...
An anal. was made of the effects of nonexponential transverse relaxation during the free precession periods of 2-dimensional NMR expts. The presence of cross-correlation between various interactions that cause relaxation, such as chem. shift anisotropy and ...
Procedures are described for automated anal. of two-dimensional NMR spectra correlating the chem. shifts of carbon-13 with the shifts of neighbor protons that are directly attached to the carbon-13 nuclei and with remote protons that have scalar couplings ...
New NMR techniques are described for transferring transverse magnetization between scalar-coupled nuclei in the rotating frame. The methods involve simultaneous spin-locking of two selected spins A and X, using cosinusoidal modulation of the radio frequenc ...
Cross-correlation between proton chem. shift anisotropy and proton-proton dipolar interactions is shown to be an important relaxation mechanism. Cross-correlation leads to a partial conversion of Zeeman order into longitudinal two-spin order. The build-up ...
A soln. is presented to the problem of phase dispersion in the resultant magnetization for pulses used for high-resoln. NMR work by demonstrating how a Gaussian pulse having an on-resonance flip angle of 270 Deg has much improved phase properties over the ...
A novel spin-echo expt. is proposed that uses semiselective Gaussian pulse cascades for refocusing in systems with homonuclear couplings. The expt. allows one to obtain evdience of differential T2 effects due to cross-correlation of proton chem. shift anis ...
The difference between 1H NMR spectra obtained during eu- and hyperglycemia exhibited well-resolved glucose peaks between 3 and 4 ppm as demonstrated by comparison with solution spectra. Estimated increases were consistent with recent 13C NMR quantitations ...
