Brillouin spectroscopic studies of the elastic properties of artificial and natural ice samples

• Main Author: Gammon, Peter Henry
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 1981
• Subjects: Sea ice
• Online Access: https://research.library.mun.ca/5765/; https://research.library.mun.ca/5765/1/Gammon_PeterHenry.pdf; https://research.library.mun.ca/5765/3/Gammon_PeterHenry.pdf

The method of Brillouin spectroscopy has been used to measure the dynamic elastic moduli of local homogeneous regions in ice samples representing four different environments of formation. These included artificial ice frozen from distilled water, clear monocrystalline glacial ice, bubbly lake ice and sea ice. Results show Brillouin spectroscopy to be an effective technique for accurately measuring the small scale elastic properties (between inclusions) of natural ice samples. – The four samples studied were found to have identical microscopic elastic properties, that is, the respective measured sets of elastic moduli showed agreement within experimental uncertainty. Accordingly, the elastic properties of homogeneous monocrystalline ice have been found not to vary with sample age, with impurities present at the time of freezing or with crystal quality. The bulk elastic properties of ice remain of course, subject to modification by differing crystal grain textures and by the presence of inclusions of various sorts. – Weighted mean adiabatic elastic moduli for homogeneous mono-crystalline ice (equivalently, local regions in polycrystalline or heterogeneous ice) have been calculated from the combined Brillouin spectroscopic data for the four types of samples. The values at -16°C were determined to be c₁₁ = 139.25 ± .41, c₁₂ = 70.82 ± .39, c₁₃ = 57.65 ± .23, c₃₃ = 150.10 ± .46, c₄₄ = 30.14 ± .11 (units of 10⁸ N/m² or kbar). A simplified linear temperature correction relation for the elastic moduli has been determined from Brillouin data obtained at -3°C and at -16°C. A full range of derived elastic parameters for monocrystalline ice and for homogeneous isotropic polycrystalline ice has been calculated. – The values for elastic moduli obtained in the present work are subject to smaller overall uncertainty than are values obtained by previous authors. Agreement of the present results with previous measurements is generally good but not in all cases within experimental uncertainty. Unnoticed systematic error in previous ...