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 14N 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 14N spinning sidebands, as illustrated by determination of the 14N 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 14N CSA for Pb(NO3)2 spinning (12 kHz) at twice the magnitude of the 14N CSA.