De-pake-ing of NMR spectra

A procedure suggested elsewhere (Bloom, Davis, and MacKay, Chem. Phys. Lett.80, 198 (1981)) for extracting the nuclear magnetic resonance spectrum of an oriented system from the spectrum consisting of a superposition of contributions from randomly oriented domains ("powder spectrum") is modified to enable its application to a wider range of systems. The method works well for the spectra associated with quadrupolar, dipolar, and anisotropic chemical or Knight shift interactions whose secular components have axial symmetry and scale as 3 cos ²θ - 1, where θ is the angle between the symmetry axis and the external magnetic field. Simulated spectra are used to explore the applicability of the method to lineshapes with different types of broadening and to lineshapes arising from nonaxially symmetric systems.