Microsecond time-resolved Fourier transform infrared analytics in a low pressure glow discharge reactor

Area of Science:

• Plasma physics
• Spectroscopy
• Chemical kinetics

Background:

• Low-pressure glow discharges are crucial in various industrial and scientific applications.
• Understanding plasma-chemical reactions requires detailed temporal and spatial resolution.
• Infrared spectroscopy is a powerful tool for identifying molecular species and their vibrational states.

Purpose of the Study:

• To design and validate a novel low-pressure glow discharge reactor for time-resolved infrared spectroscopic investigations.
• To study the dynamic evolution of infrared spectra in an air/CO2 gas mixture under electrical discharge conditions.
• To elucidate the energy transfer mechanisms involved in the excitation of carbon dioxide (CO2) molecules.

Main Methods:

• Development of a specialized low-pressure glow discharge reactor.
• Implementation of time-resolved infrared spectroscopy with microsecond resolution.
• Analysis of spectral changes in an air/CO2 gas mixture during and after plasma pulses.

Main Results:

• The infrared spectra showed significant changes in the 2400-2200 cm⁻¹ region, corresponding to the asymmetric stretch mode of CO2.
• Electrical discharge was found to strongly influence the CO2 spectra.
• Evidence of energy transfer from excited nitrogen (N2) molecules to CO2 molecules via a resonant effect was observed.

Conclusions:

• The developed reactor facilitates real-time spectroscopic analysis of plasma-discharge zones.
• The study demonstrates a reversible energy transfer mechanism between N2 and CO2 molecules, crucial for understanding plasma chemistry.
• Time-resolved infrared spectroscopy provides valuable insights into the dynamics of gas-phase reactions in electrical discharges.