A study of molecular reorientation in a series of liquid n-alkanes using light-scattering spectroscopy

Abstract

The spectra of the depolarized (VH) light scattered from the n-alkanes C₆H₁₄, C₈H₁₈, C₁₀H₂₂, C₁₂H₂₆, C₁₄H₃₀, C₁₅H₃₂ and C₁₆H₃₄ have been measured using a high resolution piezo-electrically scanned Fabry-Perot interferometer. The values of the molecular relaxation times τ _s derived from the spectra are compared with relaxation times τ _f derived from flow birefringence. The experimental results are discussed in terms of a phenomenological activation energy and also in terms of the coupling between the molecular reorientation and the hydrodynamic shear modes, allowing estimates of the strength of the coupling between these modes to be made.