Equilibrium and Non-Equilibrium Type β-Relaxations:  d-Sorbitol versus o-Terphenyl

A previous observation, which indicated that the β-relaxation intensity of o -terphenyl is sensitive to the thermal history, is substantiated by dielectric relaxation experiments. Unlike the β-processes of other materials, only the quenched glassy state of o -terphenyl displays this secondary relaxation feature. The β-intensity is observed to decay gradually upon annealing and disappears altogether in the equilibrium liquid state at T > T g . We compare the case of o -terphenyl with the concomitant signatures of d -sorbitol, which represents the more typical case of a glass-former which exhibits the slow β-process also in the liquid state including the α−β-merging scenario. We also present data of this α−β-merging for d -sorbitol confined to pores of 5 nm diameter, indicating that no longer-ranged correlations are involved in the secondary process.