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Problem Statement and Motivation

Ultra-Fast Optochemical Sensor for Express Monitoring of Oxyhydrogen Gas Mixtures in Combustion and Catalysis Eduard G. Karpov, Civil & Materials Engineering, University of Illinois at Chicago. Problem Statement and Motivation. O-radicals.

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Problem Statement and Motivation

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  1. Ultra-Fast Optochemical Sensor for Express Monitoring of Oxyhydrogen Gas Mixtures in Combustion and Catalysis Eduard G. Karpov, Civil & Materials Engineering, University of Illinois at Chicago Problem Statement and Motivation O-radicals • Measuring the concentrations of simple gas-phase radicals (H, O, OH) is difficult due to the short lifetimes • Standard methods (paramagnetic resonance, optical and mass spectroscopy, etc.) are often slow, and insufficiently focused to be applicable to local regions of interest, microflames, nanocatalysis, and other nano applications. • There is a great potential for fast and reliable sensors with a fast response, and short repetition/measurement cycle, for measuring oxyhydrogen radicals content in gas mixtures. H-radicals Key Achievements and Future Goals Technical Approach • Ultra-short response times of up to 10–7 s, and high repetition rates of 0.5-1.0 measurement per second. • High robustness and repetitiveness of the data (O and H). • Approach excludes any spurious effects of sensor surface transformation. Approach eliminates the need for a preliminary preparation of the sensor surface. • Simplicity: etalon flow can be formed by a simple pyrolytic source (typically a platinum filament); luminescence intensity is measured by a standard photometric equipment. • The approach can be extended to the analysis of (photo)-catalytic properties of solid surfaces. • “Atomic probe” procedure is developed to select an appropriate sensor core material (with dominant Eley-Rideal channel of radical recombination across the sensor range). Also, the material is selected to have luminescence properties, ZnS-Cu, ZnS-Tm, CaO-Bi, etc. Surface radical recombination invokes e-h generation with successive recombination on the luminescence centers (dopants). • The atomic probe procedure is used also to provide the etalon flow of radicals for sensor self-calibration. • Ratio of background luminescence intensity and intensity pikes due to the etalon flow is proportional to the sought concentration of radicals in the gas phase.

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