Picosecond Dynamics of Propylene Carbonate Investigated using Ultrafast Optical Kerr Effect Spectroscopy

Ultrafast optical Kerr effect (OKE) spectroscopy is used to investigate the picosecond timescale dynamics of propylene carbonate. The liquid is studied over a wide range of temperatures ranging from the deeply supercooled state through well above the melting temperature. These dynamics exhibit complex, non-diffusive behavior and are shown to be heterogeneous in nature. A simple two-state model is presented to describe the dynamics in relation to the local structure of the liquid, where a fast relaxation mechanism is associated with molecules in tightly caged configurations, whereas the slower mechanism is associated with loosely caged domains within the liquid.