Inversion-recovery cross-polarization

Polymer Dynamics. 13C spin-lattice relaxation times (Ti) were determined with either an inversion-recovery sequence (16) (for carbons observed by direct polarization) or with a modified cross-polarization experiment (17). 13C rotating-frame relaxation times (Tip(C)) were derived from measurements of the carbon signal that remained after a Tjp(C) hold time of... 

Measured via H- P cross polarization, with H inversion-recovery, at 150 MHz. Estimated error 6%. 

Measured via cross polarization, with inversion-recovery, at the frequency indicated. Only one proton spin-lattice relaxation... 

The observation of rigid and mobile phases in 15N enriched melamine-formaldehyde resins makes it possible to measure the spin-lattice relaxation times in both regions. By using standard inversion recovery and cross-polarization (86) T pulse sequences the values in the range 6-22 s and 25-69 s, respectively, were obtained for the secondary amine resonance. Shorter relaxation times in more mobile portions of the sample, as well as longer times in more rigid parts, show a similar temperature dependence with a possible minimum (around 343 K) associated with relaxation processes in the resin (53). 

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