BRILLOUIN-SCATTERING STUDY ON DYNAMIC PROPERTIES OF A VISCOELASTIC LIQUID PROPYLENE-GLYCOL USING A TANDEM FABRY-PEROT-INTERFEROMETER

Dynamic properties of propylene glycol have been investigated using a (3 + 3) pass vernier tandem Brillouin spectrometer in a temperature ra nge between 291 K and 372 K and a frequency range between 2 GHz and 48 0 GHz. In this report, we discuss the sound velocity dispersion observ ed below 20 GHz, the structural relaxation mode observed in a middle f requency range between 20 GHz and 200 GHz, and a fast relaxation mode observed above 200 GHz. From these measurements, covering a very wide frequency range, the dynamic susceptibility for light scattering has b een successfully determined at several temperatures and compared with the one obtained from Raman scattering.