Accession Number : ADA183525

Title :   Far Infrared and Dielectric Relaxation Spectra in Supercooled Water and Water + Propylene Glycol Solutions.

Descriptive Note : Technical rept.,

Corporate Author : PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY

Personal Author(s) : Boehm,L ; Smith,D L ; Angell,C A

PDF Url : ADA183525

Report Date : Aug 1987

Pagination or Media Count : 15

Abstract : We report the first measurements of the far IR absorption in supercooled water, the extend the temperature range of study of the most interesting feature, and H bond stretching mode at approx. 200/cm, to 85 C by incorporation of propylene glycol, PG, as solute. Low frequency dielectric relaxation measurements on a series of glass-forming PG + water solutions spanning the ra ge 30-100% PG when fitted to the Vogel-Tammann-Fulcher equation suggest this resonance absorption mode may be the attempt frequency for the relaxation process. Comparison of the strengths of the two dissipation regions in the same (absorptivity alpha) units shows dielectric relaxation as a weak shoulder sliding, with changing temperature, on the alpha=kf gamma edge of the quasi-resonant absorption band. For most compositions, the dielectric loss spectrum is only weakly dependent or temperature, but as the composition approaches the edge of the glass-forming region, the spectral widths become strongly temperature-dependent due, evidently, to a clustering phenomenon which results finally in an (unexpected) liquid-liquid phase separation. Keywords: spectra, dielectric relaxation, propylene glycol water solutions, phase separation, far infrared spectra.

Descriptors :   *INFRARED SPECTRA, *DIELECTRICS, *FAR INFRARED RADIATION, *PROPYLENE GLYCOL, ABSORPTION, COMPARISON, STRENGTH(GENERAL), LOSSES, SPECTRA, RELAXATION, EDGES, GAMMA RAYS, ABSORPTION COEFFICIENTS, TEMPERATURE, MEASUREMENT, PHASE, SEPARATION, WIDTH, RANGE(EXTREMES), PROPYLENE GLYCOL, SOLUTIONS(MIXTURES), LOW STRENGTH, SHOULDERS(ANATOMY), SLIDING, WATER, RESONANCE ABSORPTION, SUPERCOOLING, DISSIPATION

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE