Date of Graduation
Doctor of Philosophy in Physics (PhD)
William F. Oliver
Second Committee Member
Third Committee Member
Fourth Committee Member
Pure sciences, Glass, Pressure, Transition
This dissertation presents the results from experiments studying the pressure-dependence of properties associated with the glass transition in the glass-forming liquid cumene. Through the use of a diamond anvil cell, we achieve extremely high pressures over 40,000 atmospheres. A new technique is refined to directly measure the glass transition temperature Tg extremely accurately, and we show that thermodynamic scaling is capable of describing the liquid�glass transition boundary up to record-high pressures. Optical techniques are also implemented to probe the system dynamics in the viscous regime leading up to the glass transition. We present laser light-scattering measurements of the dynamic susceptibility spectra, obtained under isothermal conditions at 75 C, from which we measure the system's relaxation time as it slows down with increasing pressure. Through a more in-depth analysis, we determine the crossover density predicted by mode coupling theory, and by combining this with previous measurements, the dynamic crossover boundary is mapped up to record-high pressures for any system. Lastly, another isothermal light-scattering experiment probing the longitudinal and transverse acoustic modes is presented, providing an alternative probe to structural relaxation processes. Through the combination of all of these high-pressure techniques on a single glass-forming system, a much greater understanding of viscous liquids and the glass transition is achieved. Furthermore, the development of these techniques represents a major contribution to the field, allowing other researchers to perform similar high-pressure experiments on other systems.
Ransom, Timothy Craig, "Viscous Liquids and the Glass Transition at Extremely High Pressure: Optical Techniques Applied to Cumene in a Diamond Anvil Cell" (2016). Theses and Dissertations. 1534.