IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
artículos
Título:
Dynamic characterization of crystalline and glass phases of deuterated 1,1,2,2 Tetrachloroethane
Autor/es:
SILVINA C. PERÉZ; MARIANO ZURIAGA; PABLO SERRA; ALBERTO WOLFENSON; PHILIPPE NEGRIER; JOSEP LLUIS TAMARIT
Revista:
JOURNAL OF CHEMICAL PHYSICS
Editorial:
AMER INST PHYSICS
Referencias:
Lugar: New York; Año: 2015 vol. 143 p. 134502 - 134502
ISSN:
0021-9606
Resumen:
A thorough characterization of the γ, β, and glass phases of deuterated 1,1,2,2 tetrachloroethane(C2D2Cl4) via nuclear quadrupole resonance and Molecular Dynamic Simulations (MDSs) is reported.The presence of molecular reorientations was experimentally observed in the glass phase and in the βphase. In the β phase, and from MDS, these reorientations are attributed to two possible movements,i.e., a 180◦ reorientation around the C2 molecular symmetry axis and a reorientation of the moleculebetween two non-equivalent positions. In the glass phase, the spin-lattice relaxation time T 1 is ofthe order of 16 times lower than in the crystalline phase and varies as T −1 below 100 K in goodagreement with the strong quadrupolar relaxation observed in amorphous materials and in the glassystate of molecular organic systems. The activation energy of molecular reorientations in the glass phase(19 kJ/mol) is comparable to that observed in the glassy crystal of a ?molecular cousin? compound,Freon 112 (C2F2Cl4), for the secondary β-relaxation. Moreover, the on-site orientational motion oftetrachloroethane molecules offers a new indirect evidence of the prominent role of such orientational disorder in glassy dynamics.