The reflectivity of large single crystals of protonated and deuterated (TMTSF)₂Re0₄ and (TMTSF)₂BF₄ has been measured from ≈ 30 cm-¹ to ≈ 8000 cm-¹ using a Bruker IFS 113V Fourier Transform Interferometer for E / a and E / b' above and below the metal--insulator transitions at 177 K and 39 K respectively. The infrared powder absorption spectra of protonated and deuterated (TMTSF)₂Re0₄ has been measured from 200 cm˗¹ to 2000 cm˗¹. The Kramers-Kronig optical conductivity has been calculated from the reflectivity using Drude extrapolations to high frequency. The results for the conductivity for E / a show a one-dimensional density of states, characteristic of a one-dimensional semiconductor with strong electron-phonon coupling, with the vibrations appearing as resonances below the gap and as antiresonances above. The E / b' conductivity is smaller by almost two orders of magnitude than that for E / a, but displays the same semiconducting behavior. The phonons active in the E / b' polarization appear only as resonances. A normal coordinate analysis has been performed for protonated and deuterated TMTSF⁰ and TMTSF⁺. The results have been used to infer the frequencies of vibration and the deuterium shifts of TMTSF⁺⁰ׄ⁵. The molecular frequencies of vibration have been assigned on the basis of their observed frequencies and optical polarization, as well as their deuterium shifts. Some external phonons have also been assigned. The observation that many of the internal and external vibrations are split is due to the eightfold increase in the size of the unit cell (and subsequent reduction of the Brillouin zone) below the metal-insulator transition. The optical properties of the semiconducting state have been modelled for a one--dimensional molecular conductor with a twofold-commensurate charge-density wave, which accurately reproduces the effects of the lattice dimerization and the potential due to the anion chains. The calculations yield the electron-molecular-vibrational coupling constants for the totally symmetric a[formula omitted] vibrations of the TMTSF molecule. The model also yields a transfer integral of 1400 cm-¹ for both materials and semiconducting energy gaps of 2Δ = 1700 cm˗¹ and 2Δ = 1120 cm˗¹ for (TMTSF)₂ReO₄ and (TMTSF)₂BF₄ respectively. The optical conductivity in the E / b' polarization has been discussed in -terms of a two-dimensional band structure with anisotropic transfer integrals. The band structure calculations show the same general features as the measured spectra. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This work describes the synthesis pathways to the development of optically and thermally responsive nanovalves with fast response times in nanoporous membranes. As an approach, we developed synthesis pathways to couple a thermally responsive polymer with metallic nanoparticles and build a nanocomposite that synergizes the capability of metallic nanoparticles to convert light into heat, and the fast thermal response exhibited by the polymeric material. In addition, we developed a technique to immobilize the synthesized nanocomposite to the surface of nanoporous membranes, which allowed building valves with light and heat triggering responses. This dissertation describes two syntheses pathways developed to produce optically and thermally responsive nanocomposites by coupling metallic nanoparticles, gold and silver, with a thermally responsive polymer, p-N-isopropyl acrylamide (PNIPAM). The coupling is achieved by using PNIPAM as a capping and nucleating agent in the in situ redox reaction of a silver salt with sodium borohydride, and using PNIPAM as a capping and stabilizing agent in the redox reaction of a gold salt with ascorbic acid. The size and shape of the nanoparticles were controlled and the synthesized nanocomposites exhibit “cocoon-like” structures due to the PNIPAM surrounding the metal nanoparticles, giving the capability to aggregate and resolubilize, through many thermal (shown for gold and silver nanocomposites) and optical (shown by exposing to 532 nm wavelength low-power lasers) cycles. The steady state and dynamic heat conduction of the heat generated from the particles was modeled and the results agreed with the observed optical switching at our experimental conditions. Finally, a method to incorporate nanocomposites into nanoporous membranes (NPM) was developed. It involved prior immobilization of PNIPAM through plasma-induced grafting, followed by a reduction in situ of a metallic salt. The composite NPMs showed thermal responses and through simulation of heat conduction within the pores using the model developed in this work we were able to conclude that the synthesized composite membranes will exhibit optical switching when exposed to focused low power lasers. The nanovalves developed in this work have potential applications as optothermally responsive valves for the spatio-temporal delivery of bioactive agents, cell array, and advanced cell culture systems. / text