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International Journal of Photoenergy
Volume 2008 (2008), Article ID 547301, 6 pages
http://dx.doi.org/10.1155/2008/547301
Research Article

UV-Activated Luminescence/Colourimetric O2 Indicator

1Department of Pure and Applied Chemistry, Westchem Graduate School of Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, Scotland
2Chemical and Biological Sciences, Bell College of Technology, University of the West of Scotland, Hamilton ML3 0JB, Scotland

Received 26 July 2007; Accepted 6 November 2007

Academic Editor: Russell Howe

Copyright © 2008 Andrew Mills et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

An oxygen indicator is described, comprising nanoparticles of titania dispersed in hydroxyethyl cellulose (HEC) polymer film containing a sacrificial electron donor, glycerol, and the redox indicator, indigo-tetrasulfonate (ITS). The indicator is blue- coloured in the absence of UV light, however upon exposure to UV light it not only loses its colour but also luminesces, unless and until it is exposed to oxygen, whereupon its original colour is restored. The initial photobleaching spectral (absorbance and luminescence) response characteristics in air and in vacuum are described and discussed in terms of a simple reaction scheme involving UV activation of the titania photocatalyst particles, which are used to reduce the redox dye, ITS, to its leuco form, whilst simultaneously oxidising the glycerol to glyceraldehye. The response characteristics of the activated, that is, UV photobleached, form of the indicator to oxygen are also reported and the possible uses of such an indicator to measure ambient levels are discussed.