Experimental characterization of intermolecular multiple-quantum coherencepumping efficiency in solution NMR

The behavior of intermolecular multiple-quantum coherences in a variety of simple liquids with different chemical and magnetic properties is investiga ted experimentally and modeled by numerical simulations based on modified B loch equations, The effects of spin concentration, temperature, intramolecu lar conformational flexibility, chemical exchange, and spin-spin coupling o n the formation of high-order coherences are examined. It is shown that any process that makes the Larmor frequency time-dependent may interfere with the formation of these coherences. Good agreement is achieved between exper iments and simulation, using independently known values of the magnetizatio n density, the rate constants for translational diffusion, spin-spin and sp in-lattice relaxation, and radiation damping. (C) 2001 Academic Press.