Multiple quantum spin counting techniques with quadrupolar nuclei

Phase incremented and continuous irradiation multiple spin correlation methods are applied to spin 3/2 nuclei with small quadrupole couplings such as Li-7 in LiCl and are shown to successfully produce a coherently coupled dipolar spin network. Application to the analogous Na salt shows successful spin correlation evolving at a slower rate due to the weaker homonuclear dipolar coupling strength between Na nuclei. The results are analysed using a statistical approach. Spin counting is non-trivial as not only multiple quantum coherences between spins are generated but also within the quadrupolar spin levels. Na2C2O4 is investigated as a material with non-negligible quadrupole coupling and it is in this limit that the spin correlation techniques are found to break down. (C) 2004 Elsevier Inc. All rights reserved