DEUTERON TUNNELING IN H-BONDED PSEUDO-SPIN GLASSES

A measurement of the Rb-87 spin-lattice relaxation rate in a Rb-0.58(N D4)(0.42)D2PO4 single crystal in a wide temperature range allowed for a discrimination between classical thermally activated deuteron jumpin g across the potential barrier between the two equilibrium sites in th e H-bond and phonon assisted incoherent deuteron tunnelling. The resul ts show that thermally activated deuteron intra-bond jumping dominates above 55 K whereas at lower temperatures phonon assisted deuteron tun nelling becomes rate determining.