Spin–lattice relaxation of deuterons at multiaxial reorientation of the XD4 tetrahedron Original Research Article

The influence of anisotropic reorientation of XD4 tetrahedron on spin–lattice relaxation time T1 is described in terms of uncorrelated simultaneous jumps about the axes of symmetry. Tetrahedron reorientation is described as a Markovian process with a discrete set of orientational states. The analytical expressions of T1 for the considered types of multiaxial reorientation of XD4 are obtained. It is found that the dependence T1(T) can be characterized by both one and two minima upon different combinations of Cn axes. Equal sets of rotation axes with different mutual arrangements are demonstrated to bring about closely coinciding T1(T) curves. The model is applied to the analysis of the experimental temperature dependence of T1 of the AlD4− anion in LiAlD4 and Bu4NAlD4.