화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.108, No.9, 1589-1600, 2004
A novel relaxation equation of motion
We present a novel form of the equation of motion from Bloch-Wangness -Redfield theory (BWRT) that is in a representation-independent operator form. The equation has no time restrictions on it and incorporates Boltzmann equilibrium. We show that this new form gives results consistent with traditional BWRT and limits to BWRT when the additional restrictions and approximations of BWRT are applied to the new equation of motion. The new form shows how the usual equations for relaxation may be easily modified to include detailed balance and to avoid the long-standing problem that certain relaxation rates incorrectly become large when the lattice fluctuation rates become small; that is, the relaxation rates determined from this new approach avoid the BWRT "catastrophe". The new formulation leads to a more complete description of both longitudinal and transverse relaxation in magnetic resonance and takes into account the oscillatory nature of the relaxation of both transverse and longitudinal components in all motional regimes including the slow motion regime. The approach is of direct benefit to spectroscopists because it is described in terms of relaxation rates of observables.