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  • 1
    Electronic Resource
    Electronic Resource
    Multiple quantum magic-angle spinning using rotary resonance excitation (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 4618-4624 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have discovered rotary resonances between rf field strength, ω1, and magic-angle spinning (MAS) frequency, ωR, which dramatically enhance the sensitivity of triple quantum preparation and mixing in the multiple-quantum MAS experiment, particularly for quadrupolar nuclei having low gyromagnetic ratios or experiencing strong quadrupole couplings. Triple quantum excitation efficiency minima occur when 2ω1=nωR, where n is an integer, with significant maxima occurring between these minima. For triple quantum mixing we observe maxima when ω1=nωR. In both preparation and mixing the pulse lengths required to reach maxima exceed one rotor period. We have combined these rotary resonance conditions into a new experiment called FASTER MQ-MAS, and have experimentally demonstrated a factor of 3 enhancement in sensitivity in comparison to conventional MQ-MAS. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1333407
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  • 2
    Electronic Resource
    Electronic Resource
    A two-axis goniometer for sensitivity enhancement in single-crystal nuclear magnetic resonance spectroscopy (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1771-1779 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The construction of a single-crystal nuclear magnetic resonance (NMR) probe with a new two-axis geometry for the goniometer has improved the sensitivity of the NMR response from small crystals. This allows studies of the smallest crystals used so far in single-crystal NMR. The goniometer of the probe uses only two different mountings of the crystal, and the rotation axis of the goniometer is tilted 45° with respect to the direction of the magnetic field. By moving the goniometer outside the radio frequency coil, the filling factor and the probe sensitivity increase. The improved sensitivity for the probe is illustrated by the 31P-{1H} cross-polarization spectrum of a 0.088 mm3 crystal of (NH4)2HPO4 and a 87Rb single-pulse spectrum of a 0.048 mm3 crystal of RbZn2(HPO4)PO4. Moreover, the capability to determine precise parameters for the solid-state NMR interactions using the new probe is demonstrated by 23Na and 87Rb single-crystal studies of NaNO3 and RbClO4. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149667
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  • 3
    Electronic Resource
    Electronic Resource
    Combined Effect of Second-Order Quadrupole Coupling and Chemical Shielding Anisotropy on the Central Transition in MAS NMR of Quadrupolar Nuclei. 87Rb MAS NMR of RbClO4 (1995)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 10731-10735 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100027a009
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  • 4
    Electronic Resource
    Electronic Resource
    A new goniometer design for single-crystal nuclear magnetic resonance spectroscopy (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 2130-2133 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new goniometer for single-crystal nuclear magnetic resonance (NMR) spectroscopy has been constructed and built into a multinuclear X–1H double-tuned probe for cross-polarization and/or 1H decoupling. Improvements in the ease of mounting/remounting the crystal on the three rotational axes and in the accuracy of the stepwise rotation about these axes have been achieved compared to the usual cube goniometer. A similar improvement is achieved for the determination of the orientation of the crystal relative to the goniometer frame. The NMR goniometer has three dovetail mortises that enable rotation of the crystal about three orthogonal axes, all perpendicular to the magnetic field. The crystal is glued onto a tenon that fits precisely into the dovetails of the NMR goniometer and also into a slightly modified x-ray diffraction goniometer, thereby allowing a high-accuracy determination of the orientation for the tensorial NMR interactions with respect to the crystal frame. The performance of the goniometer is illustrated by single-crystal 23Na NMR spectra of NaNO3. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147026
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