Quadrupoles broadened to second order example


Quadrupolar tensor definition :
  • principal values are sorted |Vyy|<=|Vxx|<=|Vzz| note that Vxx and Vyy have signs opposite to that of Vzz - usually NMR is not sign sensitive for EFG
  • Vzz+Vxx+Vyy=0
  • etaQ is the anisotropy of the Quadrupolar tensor etaQ=Vyy-Vxx/Vzz  with 0<=EtaQ<=1
  • and thus Vxx=1/2 (-EtaQ-1)Vzz  and Vyy=1/2 (EtaQ-1)Vzz

How to Fit a MAS 2nd order broadened Quadrupolar spectrum


 Example :  23Na MAS spectrum of Nasicon - central transition fitted with a 2nd order quadrupolar lineshape  


 Example :  27Al MAS 400MHz spectrum of YAG fitted with 1st order quadrupolar for AlO6 and 2nd order quadrupolar for AlO4  


 Example :  27Al 1D Spectrum of Glass with AlO4/AlO5/AlO6 sites