title: On the theory of double quantum NMR in polymer systems: the second cumulant approximation for many spin I = 1/2 systems.
abstract: General analytical expressions for Double Quantum Nuclear Magnetic Resonance (DQ NMR) kinetic curves of many-spin I = 1∕2 systems are derived with an accuracy of the second cumulant approximation. The expressions obtained exactly describe the initial part of the kinetic curves and provide a reasonable approximation up to times of about the effective spin-relaxation time. For the case when the system contains two isolated spins, this result exactly reproduces known expressions. In the case of polymer melts, the intermolecular magnetic dipole-dipole interactions significantly influence the time dependence of the DQ NMR kinetic curves.
authors: Institute of Physics, Kazan Federal University, Kazan, 420008 Tatarstan, Russia.
authors: N
authors: N
authors: Fatkullin
authors: C
authors: C
authors: Mattea
authors: S
authors: S
authors: Stapf