Fringe-field method

Some care must be taken with fringe field methods if motional averaging of dipolar interactions is incomplete. Echoes then tend to be modulated by the so-called dipolar correlation effect [15, 16]. One can account for this phenomenon by dividing the (normalized) echo amplitudes recorded with and without gradient at the same Larmor frequency and at the same pulse intervals [11,12]. Any influence by relaxation and the dipolar correlation effect can be eliminated in this way. 

A novel one-sided NMR magnet has been developed for self-diffusion measurements in thin samples [7]. Using this technique, researchers have demonstrated measurements in bulk [BMIM][TFSI] and [BMIM][TFSI] confined in nanoporous anodized aluminum oxide membranes, as shown in Fig. 3. This operates at a proton Larmor frequency of 14.08 MFlz, and the expected appHcation is toward in situ measurements in portable energy devices. This method utilizes the fringe field to measure diffusion coefficients instead of conventional PFG-NMR. 

Silverans et studied interference effects between ground (or metastable) and excited states in a setup that is analogous to Ramsey s separated microwave field method. In comparison with other optical experiments, the interference conditions are easy to establish with fast ion beams, and the observed fringes are consistent with a Fourier analysis of the evolution in time of the laser frequency probed by the ions. ... 

Ghodrati M, Jury WA (1992) A field study of the effects of soil structure and irrigation method on preferential flow of pesticides in unsaturated soil. J Contam Hydrol 11 101-125 Gillham RW (1984) The effect of the capillary fringe on water-table response. J Hydrol 67 307-324... 

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