Memorial University DAI: A Brillouin spectroscopic study of the I-II phase transition in CH4

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Title	A Brillouin spectroscopic study of the I-II phase transition in CH4
Author	Kelly, Robin G., 1966-
Description	Thesis (M.Sc.)--Memorial University of Newfoundland, 1993. Physics
Date	1992.
Pagination	96 leaves : ill.
Subject	Methane--Spectra; Brillouin scattering;
Degree	M.Sc.
Degree Grantor	Memorial University of Newfoundland. Dept. of Physics
Discipline	Physics
Language	eng
Notes	Bibliography: leaves 91-96.
Abstract	The effects of rotation-translation (RT) coupling in solid methane (CH4), especially near the 1-11 phase transition, have been investigated using die technique in high resolution Brillouin spectroscopy. Large single crystals of methane were grown in a liquid helium cryostat and were successfully cooled down to 15.5 K using a novel cooling technique. Lane X-ray diffraction photographs were taken to determine crystal quality and the orientation of the crystal axes. Radiation from an argon laser was incident along the axis of the cell, while the scattered radiation was analyzed at 90° by a Brillouin spectrometer. -- The temperature dependence of the adiabatic elastic constants, the elasto optic coefficients, the bulk moduli and shear moduli have been determined in the temperature range i5.5 K < T < 90.4 K. The elastic constants all show acoustic anomalies at the transition temperature of 20.4 K. A theoretical analysis has shown that these anomalies are consistent with a decrease in RT coupling from the high temperature phase I to the low temperature phase II. Through an analysis of acoustic velocities in high symmetry directions, CH4 -II has shown a strong similarity to the rare gas solids, especially argon at low temperatures.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	76185157
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(11.30 MB) -- http://collections.mun.ca/PDFs/theses/Kelly_Robin.pdf
CONTENTdm file name	149293.cpd