Presentation Title

Determination of the temperature dependence of the rate constant for the reaction between atomic chlorine and acetaldehyde

Faculty Mentor

Fred Grieman

Start Date

18-11-2017 11:15 AM

End Date

18-11-2017 11:30 AM

Location

9-263

Session

Physical Sciences 3

Type of Presentation

Oral Talk

Subject Area

physical_mathematical_sciences

Abstract

Knowledge of peroxy radical chemistry is essential to a complete understanding of the effects of pollutants on ozone levels and the HOx budget in the atmosphere. This project has sought to contribute to this understanding through the study of the reaction between acetylperoxy {CH3C(O)H} and hydroperoxy (HO2) radicals at atmospherically relevant temperatures. Experimentally, we conduct these studies using the IRKS (Infrared Kinetic Spectroscopy) technique at the Jet Propulsion Laboratory. In this technique, we create chlorine radicals in a temperature-controlled flow tube through the photolysis of chlorine molecules via photolysis using a XeF excimer laser, which then go on to react with methanol, acetaldehyde, and oxygen to create the hydroperoxy and acetylperoxy radicals. We then monitor the concentrations of the radicals via infrared laser and ultraviolet lamp spectroscopy. However, the study of this reaction is complicated by the reactant creation and subsequent product chemistry under the laboratory conditions used to perform these experiments; the radical precursors and the radicals themselves undergo a complex array of reactions that must be understood for the eventual determination of the rate constants and branching ratios of the reaction of interest {that between HO2 and CH3C(O)H}. One of these reactions is the acetylperoxy creation reaction between Cl atom and acetaldehyde. We have performed experiments to determine the temperature dependence of this reaction rate constant at various atmospherically relevant temperatures.

Summary of research results to be presented

- Determination of the rate constant for the reaction between atomic chlorine and acetaldehyde at atmospherically relevant temperatures.

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Nov 18th, 11:15 AM Nov 18th, 11:30 AM

Determination of the temperature dependence of the rate constant for the reaction between atomic chlorine and acetaldehyde

9-263

Knowledge of peroxy radical chemistry is essential to a complete understanding of the effects of pollutants on ozone levels and the HOx budget in the atmosphere. This project has sought to contribute to this understanding through the study of the reaction between acetylperoxy {CH3C(O)H} and hydroperoxy (HO2) radicals at atmospherically relevant temperatures. Experimentally, we conduct these studies using the IRKS (Infrared Kinetic Spectroscopy) technique at the Jet Propulsion Laboratory. In this technique, we create chlorine radicals in a temperature-controlled flow tube through the photolysis of chlorine molecules via photolysis using a XeF excimer laser, which then go on to react with methanol, acetaldehyde, and oxygen to create the hydroperoxy and acetylperoxy radicals. We then monitor the concentrations of the radicals via infrared laser and ultraviolet lamp spectroscopy. However, the study of this reaction is complicated by the reactant creation and subsequent product chemistry under the laboratory conditions used to perform these experiments; the radical precursors and the radicals themselves undergo a complex array of reactions that must be understood for the eventual determination of the rate constants and branching ratios of the reaction of interest {that between HO2 and CH3C(O)H}. One of these reactions is the acetylperoxy creation reaction between Cl atom and acetaldehyde. We have performed experiments to determine the temperature dependence of this reaction rate constant at various atmospherically relevant temperatures.