28 August 2015 Grating-coupled surface plasmon resonance gas sensing based on titania anatase nanoporous films
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Abstract
Nanoporous TiO2 anatase film has been investigated as sensitive layer in Surface Plasmon Resonance sensors for the detection of hydrogen and Volatile Organic Compounds, specifically methanol and isopropanol. The sensors consist of a TiO2 nanoporous matrix deposited above a metallic plasmonic grating, which can support propagating Surface Plasmon Polaritons. The spectral position of the plasmonic resonance dip in the reflectance spectra was monitored and correlated to the interaction with the target gases. Reversible blue-shifts of the resonance frequency, up to more than 2 THz, were recorded in response to the exposure to 10000 ppm of H2 in N2 at 300°C. This shift cannot be explained by the mere refractive index variation due to the target gas filling the pores, that is negligible. Reversible red-shifts were instead recorded in response to the exposure to 3000 ppm of methanol or isopropanol at room temperature, of magnitudes up to 14 THz and 9 THz, respectively. In contrast, if the only sensing mechanism was the mere pores filling, the shifts should have been larger during the isopropanol detection. We therefore suggest that other mechanisms intervene in the analyte/matrix interaction, capable to produce an injection of electrons into the sensitive matrix, which in turn induces a decrease of the refractive index.
Conference Presentation
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Enrico Gazzola, Enrico Gazzola, Michela Cittadini, Michela Cittadini, Laura Brigo, Laura Brigo, Giovanna Brusatin, Giovanna Brusatin, Massimo Guglielmi, Massimo Guglielmi, Filippo Romanato, Filippo Romanato, Alessandro Martucci, Alessandro Martucci, } "Grating-coupled surface plasmon resonance gas sensing based on titania anatase nanoporous films", Proc. SPIE 9547, Plasmonics: Metallic Nanostructures and Their Optical Properties XIII, 95471D (28 August 2015); doi: 10.1117/12.2186662; https://doi.org/10.1117/12.2186662
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