Experimental depolarized Rayleigh and Brillouin spectra of liquid and supercooled liquid dibutyl phthalate (M.P. = minus;35thinsp;deg;C) are reported over the temperature range from minus;116 to 70thinsp;deg;C. The depolarized spectra exhibit a propagating transverse wave at temperatures as high as minus;21.5thinsp;deg;C, while the Brillouin spectra exhibit a kink in the longitudinal frequency shift corresponding to the glass transition temperature at approximately minus;95thinsp;deg;C, and a maximum in the linewidth at approximately 7thinsp;deg;C. A single equation from the recent theory of Wang has been used to fit the experimental depolarized spectra over the entire temperature range and values of the translation rotation coupling constant dgr;, the orientation relaxation constant Ggr;, the shear wave relaxation constant eegr;, and the elastic shear wave oscillation frequency OHgr; have been determined. The depolarized Rayleigh relaxation time tgr; is shown to obey Arrhenius type behavior with an activation energy of 6.5 kcalthinsp;molminus;1. eegr;, dgr;, and OHgr; are shown to constitute an internally consistent set of parameters describing the behavior of the propagating shear wave in a viscoelastic fluid.
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