title: Anomaly of the rotational nonergodicity parameter of glass formers probed by high field electron paramagnetic resonance.
abstract: Exploiting the high angular resolution of high field electron paramagnetic resonance measured at 95, 190, and 285 GHz we determine the rotational nonergodicity parameter of different probe molecules in the glass former o-terphenyl and polybutadiene in a model-independent way. Our results clearly show a characteristic change in the temperature of the nonergodicity parameter proving a rather sharp dynamic crossover in both systems, in contrast to previous results from other techniques.
authors.affiliation: Dipartimento di Fisica Enrico Fermi, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy2IPCF-CNR, via G. Moruzzi 1, I-56124 Pisa, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Bercu
authors.forename: M
authors.initials: M
authors.lastname: Martinelli
authors.forename: C A
authors.initials: CA
authors.lastname: Massa
authors.forename: L A
authors.initials: LA
authors.lastname: Pardi
authors.forename: E A
authors.initials: EA
authors.lastname: Rössler
authors.forename: D
authors.initials: D
authors.lastname: Leporini