Acidic ZSM-5 Zeolite-Coated Long Period Fiber Grating for Optical Sensing of Ammonia
A ZSM-5 zeolite thin film with Si/Al ratio of about 23 has been grown on a long period fiber grating (LPFG) for optical gas sensing by monitoring its resonance wavelength (λR) shift caused by molecular sorption into the zeolite cavity. The sensing selectivity, sensitivity and speed of response of the zeolite-coated LPFG (Z-LPFG) are determined by the adsorption equilibria and transport properties of the analyte molecules in the zeolite pores. The ZSM-5 zeolite was modified through ammonium ion exchange and subsequent calcination to form acidic ZSM-5 (H-ZSM-5). The surface acidified Z-LPFG (HZ-LPFG) achieved dramatically improved sensitivity and selectivity for detecting ammonia gas. Also, increasing operation temperature improves sensing selectivity for the strongly adsorbing ammonia over weakly adsorbing gases and enhances response speed but compromises detection sensitivity due to reduced amount of adsorption for ammonia.
X. Tang et al., "Acidic ZSM-5 Zeolite-Coated Long Period Fiber Grating for Optical Sensing of Ammonia," Journal of Materials Chemistry, Royal Society of Chemistry, Jan 2011.
The definitive version is available at http://dx.doi.org/10.1039/C0JM02523B
Electrical and Computer Engineering
National Science Foundation (U.S.)
United States. Department of Energy
Keywords and Phrases
ZSM-5 Zeolite Thin Film; Long Period Fiber Grating
Article - Journal
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