Discharge-flow kinetics measurements using intracavity laser absorption spectroscopy

Area of Science:

• Chemical Kinetics
• Spectroscopy
• Physical Chemistry

Background:

• Measuring reaction rates of free radicals is crucial for understanding chemical processes.
• Discharge flow techniques coupled with sensitive detection methods are needed for studying reactive species.

Purpose of the Study:

• To demonstrate Intracavity Laser Absorption Spectroscopy (ICLAS) as a viable detection method in a discharge flow tube.
• To measure the reaction rate constant for the formation of HNO from atomic hydrogen and NO.
• To explore the utility of ICLAS for kinetics measurements of reactive species.

Main Methods:

• Utilized a discharge flow tube system with helium carrier gas.
• Employed Intracavity Laser Absorption Spectroscopy (ICLAS) for sensitive detection of trace species.
• Measured the concentration of reactants and products to determine reaction kinetics.

Main Results:

• Successfully implemented ICLAS for trace species detection in a discharge flow tube.
• Determined the reaction rate constant for H + NO + M --> HNO + M (M = He) to be (4.3 +/- 0.4) x 10(-32) cm(6) molecule(-2) s(-1) at 295 K.
• The pressure and concentration ranges allowed for the limitation of competing reactive pathways.

Conclusions:

• ICLAS is a feasible and sensitive technique for detecting trace species in discharge flow systems.
• The study provides a key rate constant for the HNO formation reaction.
• ICLAS, combined with discharge flow, is a powerful tool for kinetics studies of free radicals and reactive intermediates.