Determination of nitrogen chemical shift anisotropy from the second-order cross-term in 14N MAS NMR spectroscopy

A new method for determination of nitrogen chemical shift anisotropies (CSAs) employing N-14 MAS NMR spectroscopy is presented. The method utilizes the effect of the second-order cross-term between the quadrupolar coupling and chemical shift interaction in the average Hamiltonian on the lineshape for the individual resonances within the manifold of N-14 spinning sidebands, as illustrated by determination of the N-14 CSA for Pb(NO3)(2). The second-order functionality for this cross-term ensures that the CSA cannot be averaged by MAS. This is illustrated by determination of the N-14 CSA for Pb(NO3)(2) spinning (12 kHz) at twice the magnitude of the N-14 CSA. (C) 2003 Elsevier B.V. All rights reserved.