DQ exchange experiments

Fig. 12. (a) Schematic representation of DQ exchange experiments for elucidation of slow molecular dynamics.45 (b) Calculated (black) and observed (gray) 13C-I3C DQ MAS NMR sideband patterns of crystalline poly(ethylene) yielding the dipolar coupling strength and DQ-DQ exchange sideband patterns for different jump angles. For details, see ref. 45. 

Fig. 43. Calculated sideband patterns (corresponding to the Fourier transform of the t — ti — t2 time domain data from the pulse scheme in Fig. 42) from a DQ-DQ exchange experiment, where the sideband pattern has been divided by a similar pattern obtained from the same experiment with a very short mixing time.68 This ensures that the sidebands purely reflect the mobile sites in the sample. The patterns are calculated assuming a two-site exchange through angle Ady. (a) Z)yTex = 1. (b) DijT ex— 1.5, where rex is the DQ excitation time and Dy is the dipole coupling constant between spins i and j.

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