Goldman-Shen 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). 

Figure 13. (a) The Goldman—Shen pulse sequence. The decay following the third... 

Fig, 6.1.7. Pulse sequence and magnetization recovery of the Goldman-Shen experiment. Magnetization in the rigid (crystalline) domain is randomized in time to> V 2. Recovery of magnetization of the crystalline domains, R(f), due to transfer of magnetization from noncrystalline to crystalline domains is monitored at variable times t. 

Fig. 10.11. (a) Pulse sequence for the modified Goldman-Shen experiment with detection and (b) plots of H magnetization change versus square root of the spin-diffusion time for PVPh/PEO = 58/42 at 310 K. Straight lines are drawn through the initial linear portion of the data to determine the intercept time L. (Reprinted with permission from Ref. [34]. 1992 American Chemical Society, Washington, DC.)... 

Figure 7.7 Pulse sequence for the Goldman-Shen experment. At short t, only the magnetisation from the slower decaying component is observed, whereas at longer t, spin diffusion has caused the magnetisation from the faster decaying component to reappear.

A recent example from the literature which is particularly illustrative of this approach is the so-called WISE experiment [137], in which the lineshape is detected as a function of chemical shift in a two-dimensional experiment. This sequence has also been modified to permit observation of the effects of spin diffusion in what is essentially a heteronuclear two-dimensional variant of the Goldman-Shen type experiment. This has allowed clear observation of the effects of micro heterogeneity in compatible blends of PS/PVME. 

Figure 4.12 The Goldman-Shen pulse sequence [16] for the study of spin diffusion A, short mixing time B, long mixing time. All pulse angles are 90°. The r.f. phases are indicated above the pulses. The signal after the initial 90° pulse shows both rapidly relaxing and slowly relaxing components. The terms prep, evol and det refer to the preparation, evolution and detection periods respectively...

---