Advanced Relaxometry Methods

In addition to the more simplistic relaxometric techniques outlined briefly above, more elegant approaches to relaxometry have been developed that yield more robust, specific 

To address the issue of rigid polymer components, various researchers have turned to time reversing strategies that, in a very simplified sense, restore the system s memory of magnetization lost to strong dipolar interactions. 

An alternative approach to obtaining information on polymer dynamics and network structure was developed by Ball, Callaghan, and Samulski and called the j3 function. This experiment amounts to a clever combination of various echoes (both Hahn and solid) Hke the type used to obtain Tj decay curves, and has been employed to probe interproton dipolar interactions. To explain the resultant data, a simple dynamical correlation function was introduced that depended only on the strength of the RDC and a measure of the tube disengagement time. Values extracted from data on PDMS melts were shown to be consistent with those derived via other methods [59]. These treatments were then extended 

A similar approach to ji decay in that it too relies on a combination of echoes is referred to as the dipolar correlation effect (DCE). This technique relies on a ratio of the stimulated and Hahn echoes and has also been applied to the study of silicone materials. Notably, the DCE has been invoked to study the aging of a filled silicone upon exposure to ionizing radiation [55]. These data yielded direct evidence of surface-adsorbed species and have shown the fraction of these chains to change as a function of radiation exposme. 

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