DE-PAKE-ING OF NMR POWDER SPECTRA BY NONNEGATIVE LEAST-SQUARES ANALYSIS WITH TIKHONOV REGULARIZATION

A new de-Pake-ing method is presented to calculate NMR spectra of orie nted samples from the NMR spectra of the corresponding powder samples. This task involves the numerical solution of a Fredholm integral equa tion of the first kind, i.e., a strongly ill-posed problem. The Tikhon ov regularization technique has been proved to be a powerful method fo r the treatment of such integral equations. For the first time, this t echnique is applied to the de-Pake-ing procedure. The improvement conc erning stability and reliability of the new de-Pake-ing algorithm in c omparison with the already known methods is demonstrated. Furthermore, a new technique to consider additional orientation-independent line b roadening in the de-Pake-ing procedure is introduced. (C) 1995 Academi c Press, Inc.