Browsing by Author "Nickel, Daniel Vincent"
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Item One-dimensional terahertz imaging of surfactant-stabilized dodecane-brine emulsion(2012) Nickel, Daniel Vincent; Mittleman, Daniel M.Terahertz line-images of surfactant-stabilized dodecane(C 12 H 26 )-brine emulsions are obtained by translating the emulsified region through the focus of a terahertz time-domain spectrometer, capturing a time-domain waveform at each vertical position. From these images, relative dodecane content, emulsion size, and stability can be extracted to evaluate the efficacy of the surfactant in solvating the dodecane. In addition, the images provide insight into the dynamics of concentrated emulsions after mixing.Item Terahertz Spectroscopy of Soft Condensed Matter: Single Methyl Branched n-Alkanes and Plastic-Crystals(2015-02-25) Nickel, Daniel Vincent; Mittleman, Daniel M.; Kelly, Kevin; Natelson, DouglasTerahertz time-domain spectroscopy has long been recognized as a valuable tool for characterizing the far-IR range (0.1 THz to 10 THz) properties of innumerable condensed phase materials. Soft condensed matter, a broad subcategory of condensed matter, encompasses thermally and/or mechanically deformable phases such as liquids, liquid-crystals, plastic-crystals, and polymers. With comparatively more internal degrees of freedom and weaker atomic/molecular interactions, complex phase behavior and dynamics often emerge in these materials, which generally have not been explored in the THz range. Here, temperature-dependent THz-TDS is applied to three soft condensed matter systems. Using a custom designed reflection geometry spectrometer and a novel variable path length liquid sample cell, the isotropic polarizabilities of liquid phase methyl-branched n-alkanes and their linear structural isomers are characterized and compared in the THz range. In addition, the plastic-crystal’s succinonitrile and camphor are studied using transmission geometry THz-TDS. The THz range properties and dynamics characterized in these studies, from the structure-dependent isotropic polarizabilities of prototypical liquid hydrocarbons to the complex disorder/order transitions and correlated molecular dynamics of plastic-crystals, provide valuable fundamental insight into the behavior of soft condensed matter systems.