The method of random sampling was introduced for the first time in the nutation nuclear quadrupole resonance (NQR) spectroscopy where the nutation spectra show characteristic singularities in the form of shoulders. The analytic formulae for complex two-dimensional (2-D) nutation NQR spectra (I = 3/2) were obtained and the condition for resolving the spectral singularities for small values of an asymmetry parameter η was determined. Our results show that the method of random sampling of a nutation interferogram allows significant reduction of time required to perform a 2-D nutation experiment and does not worsen the spectral resolution.
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http://dx.doi.org/10.1007/s00723-010-0148-6 | DOI Listing |
J Magn Reson
July 2024
CEISAM, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, Nantes University-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes Cedex 3, France.
Radio-Frequency (RF) pulse calibration is an essential step in guaranteeing both optimum acquisition quality in multi-pulse NMR and accurate results in quantitative experiments. Most existing methods are based on a series of spectra for which the flip angle of one or more pulses is progressively incremented, implying a significant experiment time. In order to circumvent this drawback, we have previously proposed an approach based on the acquisition of a spin echo and a stimulated echo - the MISSTEC sequence - which requires only 8 s to determine the PW-H, while it is several minutes in the case of the use of a nutation curve.
View Article and Find Full Text PDFJ Magn Reson
August 2022
Nantes Université, CNRS, CEISAM, UMR6230, F-44000 Nantes, France.
NMR sequences are composed of multiple radio-frequency pulses. Probe adjustment, sample concentration and solvent influence the loading factor, therefore these parameters also impact the validity of flip angles. The commonly used method to calibrate RF pulses is to measure a nutation curve by varying the pulse duration.
View Article and Find Full Text PDFThe method of random sampling was introduced for the first time in the nutation nuclear quadrupole resonance (NQR) spectroscopy where the nutation spectra show characteristic singularities in the form of shoulders. The analytic formulae for complex two-dimensional (2-D) nutation NQR spectra (I = 3/2) were obtained and the condition for resolving the spectral singularities for small values of an asymmetry parameter η was determined. Our results show that the method of random sampling of a nutation interferogram allows significant reduction of time required to perform a 2-D nutation experiment and does not worsen the spectral resolution.
View Article and Find Full Text PDFJ Phys Chem B
October 2007
Department of Physics, Washington University in St. Louis, One Brookings Drive, Saint Louis, Missouri 63130, USA.
A recently reported hydrogen-ice clathrate carries up to four H(2) in each large cage and one H(2) in each small cage. We report pulsed proton NMR line shape measurements on H(2)-D(2)O clathrate formed at 1500 bar and 250 K. The behavior of the two-pulse spin-echo amplitude with respect to the nutation angle of the refocusing pulse shows that intramolecular dipolar broadening, modulated by H(2) molecular reorientations, dominates the line width of the ortho-H(2).
View Article and Find Full Text PDFThe spin nutation properties of frequency selective (space selective in combination with a magnetic field gradient) trains of radiofrequency micropulses were studied in a numeric model. Two cases were considered, one simulating the 90 degrees excitation pulse in spin-echo MRI, the other the 180 degrees spin inversion pulse. Image reconstruction according to the 2-D Fourier transform technique requests that the effect of the 180 degree pulse is independent of the initial phase of the spin vector relative to the radiofrequency field.
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