| The method of spectroelectrochemical sensing is applicable to a number of chemical systems (Ru(Bipy)32+/3+, Fe(CN)63-/4-, Fe(II)/Fe(III)), and may be operated in either absorbance or fluorescence modes. One thing that remains constant in each incarnation of the sensor is an ITO-coated glass substrate, coated with a chemically selective film. The success of the sensor overall is dictated by the properties of the film. Thus much effort has been devoted to improving film properties and finding new film materials.; One goal of this work is the development of a sensor for pertechnetate anion (TcO4-), a species of concern due to its radioactivity (weak beta emitter), long half-life (2.15 x 10 5 years), and high mobility in groundwater. This dissertation describes the development, characterization and performance of two entirely new films for use in the sensor, both based on quaternized poly(4-vinylpyridine) (QPVP) as the incorporated anion exchanger. QPVP was chosen based on reports of its superior performance as an anion exchange resin for anionic forms of radionuclides. One film was prepared using sol-gel derived silica as a host, similar to previously used films, the other by simultaneous quaternization and cross-linking. QPVP-SiO 2 films demonstrated good but irreproducible response to model analytes, and exhibited good electrochemical uptake of TcO4- . Cross-linked QPVP films show great promise, demonstrating outstanding ruggedness, and good uptake properties.; Additionally, cross-linking of poly (4-vinylpyridine) via gamma- and electron-beam-irradiation was also investigated as a method of film preparation. Scanning electron microscopy investigations of sensor-related samples is also described. SEM analysis proved extremely useful in correlating deposition of metals at an ITO surface with the observed current and optical signal. Finally, the application of both QPVP films to analytes other than ferrocyanide, including TcO4- and gold nanoparticles is also described. |
PDF Full Text Request