No abstract

Nuclear spin-lattice relaxation times T 1 for protons in polycrystalline (NH4)2PbCl6 were measured by the NMR pulse method from room temperature to liquid helium temperature at the resonance frequencies 9, 22, and 42 MHz. A minimum in T 1 caused by the classical reorientation motion of the NH4 +-ion was observed at about 70 K. Parameters of the reorientational motion were deduced from the T 1 data above 60 K. Additional T 1 minima were observed below 60 K. They were interpreted in terms of the temperature dependent effective tunneling splitting of the torsional ground state of the ammonium ion.

No abstract

No abstract

No abstract