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Strong Collision Induced Spin-Lattice Relaxation for Tunneling NH4-ion Systems in the Rotating Frame

Kunihiko Morimoto
Faculty of the Integrated Arte and Sciences,
Hiroshima University , Hiroshima , Japan
Z. Naturforsch. 36a, 121-127 (1981);

[received December 4 1980*]

In order to calculate the rotating frame spin-lattice relaxation time T\ Q for tunneling NH 4ion systems at low temperature, a model of relaxation, which is available when yi?LTr U is proposed, where #L is the local dipolar field and r r the correlation time. The present model is useful especially in two cases : ( 1 ) when the NH^-ion is relatively magnetically isolated and the assumption of a common spin temperature cannot be used. ( 2 ) when the level crossing of the NH4-ion occurs in the rotating frame. In case ( 1 ), non-single exponential relaxation is predicted. In case ( 2 ), T\ Q is shown to be proportional to T , while the prediction of the weak collision theory is T\ Q oc T r ~*. The present model is compared with the strong collision theory of Slichter and Ailion.

Introduction