Meiboom Gill method

A. Methods. T measurements were made by the Carr-Purcell-Meiboom-Gill method tl4). spacings were agarose 200 sec soya fibres 300 isec raw and cooked/drained muscle 40 psec and cooked muscle 100 psec. 100 scans were accumulated in each case. 

The T and Ti values of water trapped in the silk fibroin gel were determined according to the usual inversion-recovery method and the Carr-Purcell-Meiboom-Gill method, respectively, with a JEOL FX-90Q NMR spectrometer at 90 MHz. Figure 35 shows the time dependence of the MR image of the swollen fibroin gel together with the distribution of the signal intensity of water across the sample (one-dimensional profile) after it was immersed in TEMPOL aqueous solution. 

Dinesh and Rogers [22,1] have also measured T and T2 for the proton in CHCl as a function of temperature (- 54°C to + 90 0. They employed an NMR Specialties multi-purpose NMR spectrometer. T2 was measured using the Carr-Purcell-Meiboom-Gill method and also by the adiabatic fast-passage method at room temperature. The sample of CHCl was carefully purified and degassed. The measured values around room temperature are... 

Nuclear Magnetic Resonance (NMR) Spectroscopy. Longitudinal and transverse relaxation times (Ti and T2) of 1H and 23Na in the water-polyelectrolytes systems were measured using a Nicolet FT-NMR, model NT-200WB. T2 was measured by the Meiboom-Gill variant of the Carr-Purcell method (5). However, in the case of very rapid relaxation, the free induction decay (FID) method was applied. The sample temperature was changed from 30 to —70°C with the assistance of the 1180 system. The accuracy of the temperature control was 0.5°C. 

Cosgrove and Warren 33) used the PGSE method of Packer, et al. 9). with the Meiboom-Gill rf pulse sequence 7> to investigate concentrated polystyrene solutions. 

To do this, measurements of relaxation time (spin-spin) and T2 (spin-spin) were accomplished by means of a Bruker type SXP 4/100 pulsed spectrometer. Measurements of were carried out by the method of iii5)ulse application II-T-n/2. Impulse length H/2 was 2-3 ys, and field frequency - 90 MHz. The relaxation time T2 spin-spin was determined by the "solid echo" method, when the relaxation time was in the range of 10-200 ps, and if the relaxation time was of the order of 1 ms, the Gill-Meiboom>s method was used. Separation of relaxation time components was effected using the graphical method described by Me Brierty. In order to study the specific interactions between PAN and unsaturated elastomers the mixtures of model substances, i.e. n-dodecene-1, n-dodecane and n-butyronitrile in infrared and ultraviolet were investigated by means of Pye-Unicam spectrophotometer of the SP-700 type. 

Deuterium NMR experiments were performed at 13.7 MHz on a JEOL FX 90Q spectrometer. The Ti measurements were performed using an inversion recovery sequence and the T2 values were estimated from the line widths. Because the resonances are relatively broad for the polymers in concentrated solutions, the Ta s measured were virtually the same as those measured from the Carr-Purcell-Meiboom-Gill (CPMG) method. In this case, measuring the line widths was much faster than measuring the T2 s by the CPMG method. Thus the T2 measurements were taken to be equivalent to the T2 s. 

The quadrupolar-echo experiment represents the most widely used experiment for the observation of quadrupolar nuclei.For half-integer nuelei, it may be tuned to observe only the central transition (1/2-1/2), which is perturbed by the quadrupolar interaction only to second order, thus allowing the observation of less dominant anisotropic interactions. A significant improvement in sensitivity can be obtained by ncorporating a spin-echo method such as the Carr-Purcell-Meiboom-Gill sequence into the detection period. " The powder line-shape splits into a manifold of sidebands, from which information on the homogeneous and inhomogeneous interactions can be extracted from the line-shape of the sidebands and their envelope, respectively. 

Meiboom-Gill modification of the Carr-Purcell pulse method. 

The Cl relaxation rate of the free hydrated perchlorate ion can be obtained by extrapolation to infinite dilution of experimental data for aqueous perchlorate solutions. In most studies (e.g. Refs. [45 121 280 383 494]), magnetic field inhomogeneity was appreciable and much too low relaxation times were obtained. Recent studies in our laboratory [136 496] have given an infinite dilution value of 270 ms for both T (180°-t-90° pulse sequence) and (Meiboom-Gill modification of the Carr-Purcell method) at 28°C. 

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