title: Fluorescence characteristics of Cu-ZSM-5 zeolites in reactive gas mixtures: mechanisms for a fiber-optic-based gas sensor.
abstract: In situ measurements of the fluorescence spectra, intensity, and response time were made at elevated temperatures (~500 degrees C) for samples of Cu-ZSM-5 exposed to dilute mixtures of O(2) in N(2) and to various O(2)-reductant combinations in N(2). The results of these experiments are interpreted with a physical model of the oxidation/reduction kinetics of the copper ions. The fluorescence signal depends strongly on the gas composition, providing a mechanism for a gas composition sensor. A prototype sensor configuration is described that uses a visible (488-nm) excitation source and a fiber-optic geometry to generate and detect the fluorescence. The results indicate that for a weakly reducing gas the fluorescence signal correlates well with the oxygen concentration, whereas for strongly reducing gases the signal correlates more closely with the reductant-to-oxidant ratio.
authors.forename: J T
authors.initials: JT
authors.lastname: Remillard
authors.forename: B D
authors.initials: BD
authors.lastname: Poindexter
authors.forename: W H
authors.initials: WH
authors.lastname: Weber