9623536 Sullivan This project will investigate the dynamical properties of frustrated quench-disordered systems at low temperatures. These studies will focus on determining the important low-energy collective excitations in prototypical orientation glasses (orthoand para-dihydrogen and dinitrogen-argon solid mixtures), and the behavior of quantum quadrupoles in reduced geometries - two dimensional arrays and surface-melted quantum latticed fluids. The proposed experiments involve several different NMR and thermodynamic measurements to determine the nature of the lowfrequency thermal relaxation and the effect of lattice geometry on the ordering of classical and quantum rotors in orientational glasses. New experiments will also probe quantum exchange in multilayers of dihydrogen and in helium-3 films physisorbed on square-lattice substrates for which the combined effects of frustration and disorder are predicted to lead to nuclear spin glass phases. The project is of fundamental character but the results may provide insights into the properties of glasses which are widely employed in technical and commercial applications. %%% This project will investigate the dynamical properties of frustrated, quench-disordered systems at low temperatures. These studies will focus on determining the important low-energy collective excitations in prototypical orientation glasses (orthoand para-dihydrogen and dinitrogen-argon solid mixtures), and the behavior of quantum quadrupoles in reduced geometries - two dimensional arrays and surface-melted quantum latticed fluids. The proposed experiments involve several different NMR and thermodynamic measurements to determine the nature of the lowfrequency thermal relaxation and the effect of lattice geometry on the ordering of classical and quantum rotors in orientational glasses. New experiments will also probe quantum exchange in multilayers of dihydrogen and in helium-3 films physisorbed on square-lattice substrates for which the combined effects of frustration and disorder are predicted to lead to nuclear spin glass phases. The project is of fundamental character but the results may provide insights into the properties of glasses which are widely employed in technical and commercial applications. ***
