Broadband Time-Resolved Absorption and Dispersion Spectroscopy of Methane and Ethane in a Plasma Using a Mid-Infrared Dual-Comb Spectrometer

Conventional mechanical Fourier Transform Spectrometers (FTS) can simultaneously measure absorption and dispersion spectra of gas-phase samples. However, they usually need very long measurement times to achieve time-resolved spectra with a good spectral and temporal resolution. Here, we present a mi...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2020-11, Vol.20 (23), p.6831
Main Authors: Abbas, Muhammad Ali, Dijk, Luuk van, Jahromi, Khalil Eslami, Nematollahi, Mohammadreza, Harren, Frans J M, Khodabakhsh, Amir
Format: Article
Language:English
Subjects:
Bandwidths
Broadband
dual frequency comb spectroscopy
electrical discharge plasma
Ethane
Fast chemical reactions
Fourier transform spectrometers
Fourier transforms
Hydrocarbons
Infrared spectrometers
Lasers
Light
Methane
mid-infrared absorption and dispersion spectroscopy
Molecular absorption
Plasma
Plasma jets
Recombination reactions
Sensors
Spectra
Spectral resolution
Temporal resolution
Time measurement
time-resolved plasma kinetics
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Summary:Conventional mechanical Fourier Transform Spectrometers (FTS) can simultaneously measure absorption and dispersion spectra of gas-phase samples. However, they usually need very long measurement times to achieve time-resolved spectra with a good spectral and temporal resolution. Here, we present a mid-infrared dual-comb-based FTS in an asymmetric configuration, providing broadband absorption and dispersion spectra with a spectral resolution of 5 GHz (0.18 nm at a wavelength of 3333 nm), a temporal resolution of 20 μs, a total wavelength coverage over 300 cm and a total measurement time of ~70 s. We used the dual-comb spectrometer to monitor the reaction dynamics of methane and ethane in an electrical plasma discharge. We observed ethane/methane formation as a recombination reaction of hydrocarbon radicals in the discharge in various static and dynamic conditions. The results demonstrate a new analytical approach for measuring fast molecular absorption and dispersion changes and monitoring the fast dynamics of chemical reactions over a broad wavelength range, which can be interesting for chemical kinetic research, particularly for the combustion and plasma analysis community.
ISSN:1424-8220
1424-8220
DOI:10.3390/s20236831