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Title: Optical thin film sensors for the determination of aqueous halide ions
Author: Geddes, C. D.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1996
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Thin film optical sensors in which a halide sensitive fluorophore is immobilised in a thin (~ 50 micron) polymer film have been developed and characterised. The sensor films use rhodamine, 6-methoxyquinoline or harmane dyes which have been functionalised and bound to a hydrophilic copolymer. The selection, synthesis, functionalisation, and polymer-binding of the dyes is described, as is the synthesis and physical characterisation of the polymer supports. Two hydrophilic copolymers have been synthesised and characterised and twenty novel halide sensitive compositions have been synthesised, or formulated, and studied. Steady-state luminescence spectroscopy and single photon counting time resolved emission spectroscopy have been used to characterise the luminescence spectra and emission decay kinetics of the lumophores, both in free solution and bound and unbound in polymer films. For all dye/polymer formulations studied the emission decay kinetics are complex. Fitting to discrete exponential analysis gives at least two, and often three decay components, while distribution analysis often gives either a very broad distribution or even groups of distributions. As a consequence the steady state response gives non linear Stern-Volmer analysis when examined over a wide dynamic range. Even so, a reasonable linear Stern-Volmer response is observed for halide over physiologically and technologically important concentration ranges. The sensor films described in this work are reversibly capable of determining aqueous iodide and halide with ~ 4% accuracy at concentrations of around 0.001 mol dm-3. The 90% response time to molar halide is ~ 30 s. A combination of sensor films allows the simultaneous and rapid determination of both I- and Br- in a mixed halide solution. These sensors are potentially useful for the online determination of aqueous halide in a variety of technological applications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available