Dipolar filter pulse sequence

NMR is particularly suited for the measurement of domain sizes in the range of 5 - 20oA (145), which can be probed with a spin diffusion experiment, e.g., Goldman-Shen sequence (146) and dipolar filter pulse sequence (147). The use of multidimensional techniques to study length scales in heterogeneous polymers has been previously reviewed by Spiess (148). 

Fig. 10.3.7 Pulse sequence for spin-diffusion imaging with ID spatial resolution [Wei8] and effect of mobility filters, (a) The magnetization source is selected by the dipolar filter which suppresses the magnetization in the sink. During the spin-diffiision time the magnetization dif ses from the source to the sink, (b) The dipolar filter selects magnetization from chain segments which are highly mobile and intermediately mobile. By use of a lineshape filter the signal loss is analysed only for the mobile components. IP(Tc) is the probability for a particular correlation time to arise in the sample. It is essentially the spectral density of motion.

Fig. 11 (a, d) Pulse sequences for dipolar filter signal editing, where Tr denotes one... 

Fig. 4. A schematic diagram of the 2D PDLF (PELF) method using the BLEW-48 sequence for 1H-1H dipolar decoupling. CP denotes cross polarization. The last two jt/2 pulses of the S spin act as a Z filter. (Reproduced by permission of Elsevier Sicence.)...

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