Mixing Properties and Solubility of Atomic and Molecular Species in Cryosolids
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Exoplanetary research has shown that there are compositions of nitrogen (N2) and methane (CH4) on some planet surfaces. The following thesis studies these compositions in a vacuum state to mimic the conditions of outer space. It can then serve as a reference for future astronomical research. The solubility of nitrogen in methane (or vice versa) at cryogenic temperatures has previously been studied in the 1980s and has created a framework for what structural changes can be expected for methane and nitrogen co-deposition. Additionally, data collected from pure N2 and CH4 allowed a quantitative assessment between the Hard X-ray Micro-Analysis (HXMA) and Brockhouse beamlines at the Canadian Light Source (CLS). This was achieved by depositing CH4 and N2 at varying concentrations on a diamond substrate at cryogenic temperatures (10 K). X-rays penetrated through the sample and a unique diffraction pattern was obtained for each sample set in a time-resolved manner. Diffraction patterns were captured as each sample set was warmed to the melting point of the substances within it. Rietveld analysis was used to refine the diffraction patterns and calculate lattice parameters to model the crystal structure of each compound. The results showed that while the Brockhouse beamline produced diffraction patterns at higher scattering angles, the HXMA beamline produced better refinable data indicating better quality data. The type of leak valve for the gases that were used may have been a contributing factor in this research and so repeating the experiment is required and adjusting the flow rate of each valve to allow a fair comparison between the two. The analysis of the lattice parameters for both beamlines showed that the results from both the HXMA and Brockhouse beamlines agreed with what has been previously observed validating the reliability of the results. Next, a new phase of methane was observed at 37 K, which is further analyzed and discussed. Finally, the co-deposition of methane and nitrogen showed that the expected deposition ratios did not correspond with the observed ratios. This could be due to the individual molecular properties, the surface-molecule tension, or the quantity of the substance that was deposited.
DegreeMaster of Science (M.Sc.)
DepartmentPhysics and Engineering Physics
CommitteeChang, Gap-soo; Urquhart, Stephen; Koustov, Sasha; Scott, Robert
cryosolids, XRD, x-ray diffraction, HXMA, Brockhouse, CLS, Methane, nitrogen, exoplanets, energy storage, lattice parameters