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Title:Measuring Changes in Optical Constants of Tungsten Oxide, Tin Oxide, Zinc Oxide and Palladium for Gas Sensing Applications
Author(s):Chang, Chia-Lun
Contributor(s):Goddard, Lynford
gas sensors
hydrogen sensing
optical constants
tungsten oxide
tin oxide
zinc oxide
Abstract:Hydrogen is seen as a promising alternative energy source, but its potential to ignite at a concentration as low as 4% in air is a concern. The motivation is to determine whether certain materials may be sensitive to hydrogen and exhibit a fast enough response time to be viable for hydrogen sensing applications. Thin films consisting of WO3, Sn2, ZnO, or Pd deposited on SiO2 substrates were tested. The first step involves taking measurements of the thin films with bariable angle spectroscopic ellipsometer (VASE). Complex refractive index, n and k, in air of WO3, SnO2, and Pd were then derived through modeling and fitting of the data. The second step involves measuring changes in the reflection/transmission of light through the thin films while flowing hydrogen mixed with nitrogen at various concentrations. Conclusions may be drawn as to how the complex refractive index of the materials may have changed due to the presence of hydrogen.
Issue Date:2010-05
Publication Status:unpublished
Peer Reviewed:not peer reviewed
Date Available in IDEALS:2014-01-17

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