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1.4 CHEMICAL SCIENCES
In this work the impact of nanomaterial, specifically silver nanostructures, on sensing techniques is investigated. The work can be divided in to three sections, preparation and characterisation of silver nanoparticles, their application as a nanocomposite based chemiresistor humidity sensing device and finally their application within the surface enhanced (resonance) Raman spectroscopy, SE(R)RS, technique. In the first study silver nanoparticles were prepared as aqueous colloidal dispersions. The colloids were of either a defined diameter (average diameter ~ 20 nm) with high silver loading or lower loaded colloids of tuneable morphology and hence optical properties. In a subsequent study the high load colloid when cast on platinum interdigital electrodes as a nanocomposite coating proved to be useful as a humidity sensor. The sensor gave a reversible, selective and rapid response which was proportional to humidity levels within the range of 10% RH to 60% RH. An investigation into the mechanism of the sensor’s response was conducted and the response was found to correlate well with a second order Langmuir adsorption model. The final study was multi faceted as it first determined the suitability of the tuneable colloids as SE(R)RS substrates using a number of probe molecules. A clear sensing trend was observed, where the Raman signal emitted was significantly enhanced by the addition of silver nanoparticles. This prompted an additional investigation where both colloids were again cast as films (fabricating alternative SERS substrates) to determine the degree outside factors could influence the enhancement seen by the SERS technique. The suitability of the SERS substrates in a real world application was investigated, with SERS being used to monitor the action mechanism of components of a commercially available volatile corrosion inhibitor.
Power, A.: The Preparation and Characterisation of Silver Nanomaterials and Their Application in Sensing Techniques. Doctoral Thesis. Dublin Institute of Technology, 2011