title: On the ergodicity of supercooled molecular glass-forming liquids at the dynamical arrest: the o-terphenyl case.
abstract: The dynamics of supercooled ortho-terphenyl has been studied using photon-correlation spectroscopy (PCS) in the depolarized scattering geometry. The obtained relaxation curves are analyzed according to the mode-coupling theory (MCT) for supercooled liquids. The main results are: i) the observation of the secondary Johari-Goldstein relaxation (β) that has its onset just at the dynamical crossover temperature TB (TM > TB > Tg); ii) the confirmation, of the suggestion of a recent statistical mechanical study, that such a molecular system remains ergodic also below the calorimetric glass-transition temperature Tg. Our experimental data give evidence that the time scales of the primary (α) and this secondary relaxations are correlated. Finally a comparison with recent PCS experiments in a colloidal system confirms the primary role of the dynamical crossover in the physics of the dynamical arrest.
authors.affiliation: 1] Dipartimento di Fisica e Scienze della Terra, Università di Messina I-98168, Messina, Italy [2] Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge MA 02139.
authors.forename: Francesco
authors.initials: F
authors.lastname: Mallamace
authors.affiliation: Dipartimento di Fisica e Scienze della Terra, Università di Messina I-98168, Messina, Italy.
authors.forename: Carmelo
authors.initials: C
authors.lastname: Corsaro
authors.affiliation: CNR-IPCF Istituto per i Processi Chimico-Fisici, I-98158 Messina Italy.
authors.forename: Nancy
authors.initials: N
authors.lastname: Leone
authors.affiliation: CNR-IPCF Istituto per i Processi Chimico-Fisici, I-98158 Messina Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Villari
authors.affiliation: CNR-IPCF Istituto per i Processi Chimico-Fisici, I-98158 Messina Italy.
authors.forename: Norberto
authors.initials: N
authors.lastname: Micali
authors.affiliation: Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge MA 02139.
authors.forename: Sow-Hsin
authors.initials: SH
authors.lastname: Chen