title: Precise dipolar coupling constant distribution analysis in proton multiple-quantum NMR of elastomers.
abstract: In this work we present an improved approach for the analysis of (1)H double-quantum nuclear magnetic resonance build-up data, mainly for the determination of residual dipolar coupling constants and distributions thereof in polymer gels and elastomers, yielding information on crosslink density and potential spatial inhomogeneities. We introduce a new generic build-up function, for use as component fitting function in linear superpositions, or as kernel function in fast Tikhonov regularization (ftikreg). As opposed to the previously used inverted Gaussian build-up function based on a second-moment approximation, this method yields faithful coupling constant distributions, as limitations on the fitting limit are now lifted. A robust method for the proper estimation of the error parameter used for the regularization is established, and the approach is demonstrated for different inhomogeneous elastomers with coupling constant distributions.
authors.affiliation: Institut für Physik-NMR, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, D-06120 Halle, Germany. walter.chasse@physik.uni-halle.de
authors.forename: Walter
authors.initials: W
authors.lastname: Chassé
authors.forename: Juan
authors.initials: J
authors.lastname: López Valentín
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Genesky
authors.forename: Claude
authors.initials: C
authors.lastname: Cohen
authors.forename: Kay
authors.initials: K
authors.lastname: Saalwächter