3 May 1999 New planar waveguide attenuated total reflectance techniques for organic thin film spectroscopy and chemical sensing
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Proceedings Volume 3602, Advances in Fluorescence Sensing Technology IV; (1999) https://doi.org/10.1117/12.347515
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States
Abstract
The planar integrated optical waveguide (IOW) is an inherently sensitive geometry for attenuated total reflection (ATR) spectroscopy of interfacial samples. A major disadvantage that has limited its wider use is the difficulty of measuring broadband spectra. Due to the quantized nature of light propagation in a planar IOW, conventional grating and prism couplers are efficient only over a narrow (less than 5 nm) spectral range at a given launch angle. We have developed a multichannel spectrometer capable of measuring a broadband visible ATR spectrum at the surface of a single mode, planar waveguide. The bandwidth is greater than 150 nm, which makes it possible to measure spectra of very weakly absorbing molecular films. We have also developed an electrochemically- active, planar IOW (EA-IOW) that combines the information content of spectroelectrochemistry with the sensitivity of the single mode planar waveguide geometry. An evaluation of this device has demonstrated that highly sensitive spectroelectrochemistry of surface confined films can be performed; the estimated pathlength enhancement is ca. 4,000 relative to a transmission geometry.
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Darren R. Dunphy, Sergio Brito Mendes, Lifeng Li, James J. Burke, John E. Lee, Neal R. Armstrong, S. Scott Saavedra, "New planar waveguide attenuated total reflectance techniques for organic thin film spectroscopy and chemical sensing", Proc. SPIE 3602, Advances in Fluorescence Sensing Technology IV, (3 May 1999); doi: 10.1117/12.347515; https://doi.org/10.1117/12.347515
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