Measurements of the proton spin-lattice relaxation dispersion were carefully carried out using the fast field cycling NMR technique. More than two chemically nonequivalent nitrogen nuclei were detected from the quadrupole dip spectrum. We conclude that the HpAB biaxial smectic-C local structure is composed of bimolecular unit cells.

• Received 19 January 1996

DOI:https://doi.org/10.1103/PhysRevLett.76.3983