title: From boiling point to glass transition temperature: transport coefficients in molecular liquids follow three-parameter scaling.
abstract: The phenomenon of the glass transition is an unresolved problem in condensed matter physics. Its prominent feature, the super-Arrhenius temperature dependence of the transport coefficients, remains a challenge to be described over the full temperature range. For a series of molecular glass formers, we combined τ(T) collected from dielectric spectroscopy and dynamic light scattering covering a range 10(-12) s < τ(T) < 10(2) s. Describing the dynamics in terms of an activation energy E(T), we distinguish a high-temperature regime characterized by an Arrhenius law with a constant activation energy E(∞) and a low-temperature regime for which E(coop)(T) ≡ E(T)-E(∞) increases exponentially while cooling. A scaling is introduced, specifically E(coop)(T)/E(∞) [proportionality] exp[-λ(T/T(A)-1)], where λ is a fragility parameter and T(A) a reference temperature proportional to E(∞). In order to describe τ(T) still the attempt time τ(∞) has to be specified. Thus, a single interaction parameter E(∞) describing the high-temperature regime together with λ controls the temperature dependence of low-temperature cooperative dynamics.
authors.affiliation: Universität Bayreuth, Experimentalphysik II, D-95440 Bayreuth, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schmidtke
authors.forename: N
authors.initials: N
authors.lastname: Petzold
authors.forename: R
authors.initials: R
authors.lastname: Kahlau
authors.forename: M
authors.initials: M
authors.lastname: Hofmann
authors.forename: E A
authors.initials: EA
authors.lastname: Rössler