CPMG method

F. Girard, P. Poulet, I.J. Namer, J. Steibel, J. Chambron, Localized T-2 measurements using an osiris-CPMG method—application to measurements of blood oxygenation and transverse relaxation free of diffusion effect, NMR Biomed. 7 (1994) 343-348. 

Figure 7.23 Applications of the NMR-MOUSE to elastomer materials (a) T2 values for a curing series of carbon-black filled NR. Comparison of values obtained at high homogeneous field (DMX 300) and with the NMR-MOUSE, (b) cross-link series of unfilled SBR with different sulfur content, (c) T2 versus glass-transition temperature Tg of unfilled SBR by the CPMG and the steady-state CPMG methods, (d) normalized Hahn-echo decay curves for poly(butadiene) latex samples. Different decay rates are obtained for small medium and large cross-link densities...

CPMG) 72 determined by CPMG method. 72(Avi/2) 72 determined from linewidth. 

Fig. 3.4.1 Homogeneously and inhomogeneously broadened lines, (a) Echo train generated by repeated refocussing of the FID (CPMG method, cf. Fig 2.2.10(b)). (b) The Fourier transform of the slowly decaying echo envelope is the homogeneously broadened line, (c) The Fourier transform of the fast decaying echo is the inhomogeneously broadened line.

Fig. 9.3.15 Analysis nf a section from a conveyor bell with steel cords by the CPMG method starting from thermodynamic equilibrium and from dynamic equilibrium corresponding to partial. saturation, (a) Sketch of the sample and positions of measurements, (b) The transverse relasaiion times for one side of the belt reveal homogeneous matcriat. (c) The transverse relaxation limes for the other side indicate considerable inhomogeneity.

Suppose we had decided to measure this Tg without using the CPMG method. From the relation... 

Davis DG, Perlman ME, London RE (1994) Direct measurements of the dissociation-rate constant for inhibitor-enzyme complexes via the T-l-Rho and T-2 (Cpmg) methods. J Magn Reson Ser B 104 266-275... 

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. 

Spin- spin relaxation is usually determined applying spin echoes (Hahn-Echo, CPMG method), which delete other influences such as Bo inhomogeneity. The spin-lattice relaxation time Ti is measured by detecting the relaxation after inverting Mo by a 180° pulse (inversion recovery method). 

In the CPMG method, a 180° pulse is applied along the y axis instead of the jc axis, so that the spin flips around... 

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