Attenuated total reflectance spectroscopy of coumarin organosilane molecules adsorbed on a fused silica surface |
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Authors: | Maria Antoaneta Bratescu Nagahiro Saito |
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Institution: | a Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan b EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan |
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Abstract: | Attenuated total reflectance (ATR) spectroscopy was used to investigate the adsorption of coumarin organosilane molecules onto a fused silica surface. The difference between the absorption spectra of the molecules on the surface and in solution was explained by the interaction of the adsorbed coumarin organosilane molecules with the hydroxyl groups on the fused silica surface. This interaction produces a perturbation of the π electron distribution and the electronic transitions of the coumarin chromophore of the organosilane molecules adsorbed on the surface. From the kinetics adsorption curves, the calculated enthalpy values of 74.8 ± 5.2 kJ mol−1 and free energy of −38.22 ± 0.70 kJ mol−1 at 23 °C indicates a chemisorption process. The high sensitivity of ATR spectroscopy allows the detection of a monolayer formed by a 10 nM concentration of coumarin organosilane molecules, which covers more than half of the maximum surface coverage at 60 °C. |
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Keywords: | 68 43 Mn: Adsorption kinetics 78 40 &minus q: Absorption and reflection spectra: Visible and ultraviolet |
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