ANALYSIS OF RAYLEIGH LIGHT-SCATTERING SPECTRA OF PIVALIC ACID IN PLASTIC-PHASE AND LIQUID-PHASE

The shape of integral intensity of the depolarized component of Raylei gh light scattering on molecules of pivalic acid has been analyzed in the temperature range covering partly plastic and liquid phase. The oc currence of fast reorientations of pivalic acid monomers, earlier sear ched for by other authors, has been confirmed. This kind of motion was observed only in the liquid phase. The motion in the plastic phase is , as earlier established, a slow reorientation which involves breaking up of the double hydrogen bonds joining two adjacent molecules of piv alic acid and formation of a new bond with one of the twelve closest n eighbours. The decay constant of the pure interaction-induced processe s in the liquid and plastic phase as well as the squares of the effect ive anisotropy of the optical polarizability and anisotropy due to the pure interaction-induced processes were determined. A comparative ana lysis of integral intensity of the depolarized components at the trans ition from the plastic to the liquid phase, was performed for pivalic acid and succinonitrile. (C) 1997 American Institute of Physics.