CPMG echo train

Figure 7.22 The NMR-MOUSE (a) Schematic. The NMR sensor consists of an u-shaped permanent magnet with a solenoidal rf coil placed in the gap. (b) Photo of the NMR-MOUSE testing a tyre, (c) Example of a train of successive Hahn echoes generated according to Carr, Purcell, Meiboom and Gill (CPMG echo train) for carbon-black filled SBR measured by the NMR-MOUSE. The time constant of the echo-envelope defines T...

Fig. 5.4.11 [Cal 11 ] Modulated gradient NMR for probing spectral densities of diffusive translational motion. The pulse sequence (left) consists of a CPMG echo train with interdispersed gradient pulses G(t) which produces the time-dependent wave vector k(t). The spectrum K(co) of k(t) probes the spectral density of diffusive motion at a single frequency (right).

The T2 distribution has applications as diverse as petroleum geology and bread making. It distribution has been applied in the petroleum industry for many years to characterize rock cores to obtain pore size distributions in well-logging operations. Rock cores from oil wells are filled with water or oil. The NMR CPMG echo train is acquired in a TD-NMR instrument and the T2 distribution is obtained. This is essentially a mirror image of pore size distribution, as water in small pores is more restricted it is less mobile (short T. Water in large pores has more freedom to move (long Tj). 

Figure 3.72 The inverse Laplace transformation is applied to a T2 decay signal (the CPMG echo train) to obtain a continuous distribution of 72. (Courtesy of Bruker Optics, Inc., www.bnjker.com.)...

The D-T2 distributions were measured by a stimulated echo sequence followed by a CPMG echo train. The Tx-T correlation measurements were performed by inversion recovery preparation and a subsequent CPMG. As relaxation and diffusion parameters are different for water, fat, proteins and other macromolecules, separate data treatments can be made for fat and water behavior in the different dairy products ... 

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