Solvation dynamics in the plastic crystal and supercooled liquid state of ethanol

The dynamics of ethanol in its plastic crystalline and supercooled liquid state has been measured using triplet state solvation dynamics techniques. This study focuses on temperatures near the respective glass transitions T_g of the two distinct phases, where the structural relaxation times are between 1 ms and 10 s. In the plastic crystal, the correlation times of the Stokes shift dynamics match the longitudinal time constants of the system as derived from dielectric relaxation data. Additionally, a maximum of the time resolved optical linewidths is indicative of heterogeneous dynamics in the plastic crystal. The supercooled liquid state is obtained after quenching the liquid from room temperature to below T_g and displays relaxation times that are a factor of 100 faster compared with the plastic crystal at the same temperature. The results do not reveal different translational contributions to solvation for the two phases.