Chapter 8: Impact of Exchange on Relaxation in Heterogeneous Media Check Access

Exchange is an important issue in nuclear magnetic relaxation in multiphase and multicomponent systems. Its kinetics can be determined by thermal activation or by diffusion to and from phase boundaries. Depending on the system properties, the exchange rates can be extremely different. Limits with respect to relaxation and correlation time scales are discussed. In particular, this concerns the case of exchange between two phases with different relaxation properties. A number of application examples are outlined, including the Brownstein/Tarr model of liquids in pores and pore surface relaxation due to ‘reorientation mediated by translational displacements’.