NUCLEAR-MAGNETIC-RESONANCE LINE-SHAPES OF DOUBLE AND TRIPLE QUANTUM COHERENCES OF SPIN 3/2 NUCLEI

Nuclear magnetic resonance (NMR) line shapes of double and triple quantum coherences were calculated for spin 3/2 nuclei over a wide range of reorientation times. It is shown that for slow rotating molecules the dynamic shifts of all the coherences are a result of adiabatic averaging of the powder spectra. Line shapes are shown to be single Lorentzians far beyond the range of rotational motion, where Redfield's theory is valid. Analytical expressions for linewidths and dynamic shifts are given for the whole range of motion for which the line shape is Lorentzian. It is suggested that the high ratio between the dynamic shift and the linewidth for the triple quantum coherence can make it possible to distinguish between sodium nuclei in environments with different rotational mobility and quadrupole interactions.