The NMR-WEBLAB: an internet approach to NMR lineshape analysis

The nuclear magnetic resonance (NMR) WEBLAB is described, providing an interactive tool for analyzing NMR spectra of solids and anisotropic liquids to elucidate their molecular dynamics. It is a collection of programs freely available over the Internet at http://www.mpip-mainz.mpg.de/weblab40/ that permit the interpretation of one-dimensional NMR spectra in the case of motions occurring on a cone and of two-dimensional exchange NMR data for discrete jumps. The programs are described in detail and analytical formulae for the averaged interaction tenser components that govern the spectra in the fast motional limit are derived in an appendix. To facilitate the validation of the results obtained from the WEBLAB, we present examples for two- and three-site jumps and demonstrate how WEBLAB can be utilized for analyzing more complex motions around more than one axis as met, e.g., in poly(diethysiloxane), where experimental data are available.