Investigations into the response of an optical gas sensor based on polymeric LB films

The response of an NO 2 sensing system based on LB films of a polysiloxane with azobenzene chromophoric side-chains has been investigated. Changes in absorbance on exposure to 100 ppm NO 2 have been recorded using UV-visible absorption spectroscopy from which changes in extinction coefficient ( Δ k...

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Bibliographic Details
Published in:Supramolecular science 1997-09, Vol.4 (3), p.427-435
Main Authors: Parry, D.A., Mat Sallah, M., Miller, L.S., Peterson, I.R., Hollyoak, R.
Format: Article
Language:English
Subjects:
Langmuir-Blodgett film
optical gas sensing
polysiloxane
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Summary:The response of an NO 2 sensing system based on LB films of a polysiloxane with azobenzene chromophoric side-chains has been investigated. Changes in absorbance on exposure to 100 ppm NO 2 have been recorded using UV-visible absorption spectroscopy from which changes in extinction coefficient ( Δ k ≈ 0.033 at 500 nm) have been determined. Shallow angle X-ray reflectivity (SAXR) studies indicate a change in layer thickness from 2.10nm in air to 2.31 nm in 10000 ppm NO 2 together with loss of Bragg detail. Changes in real refractive index ( Δn ≈ 0.107 over most of the visible region) for films in air and 100 ppm NO 2 have been deduced from reflectance spectra.
ISSN:0968-5677
DOI:10.1016/S0968-5677(97)00026-6