Mid-infrared dual frequency comb spectroscopy for combustion analysis from 2.8 to 5 μm

We demonstrate the application of mode-locked mid-infrared dual frequency comb spectroscopy for combustion analysis. With two settings of the same dual-comb system, the measurement spans 1500 cm(-1) from 2.8 to 5 mu m with 0.0067 cm(-1) (200 MHz) point spacing, or almost a quarter-million discrete comb modes. Using this broadband spectrometer, we quantify the pyrolysis and smoldering combustion of wood samples. Specifically, we measure 20-second time-resolved mole fractions of CH4, H2O, two isotopologues of CO2 ((CO2)-C-12-O-16 , (CO2)-C-13-O-16), two isotopologues of CO ((CO)-C-12-O-16, (CO)-C-13-O-16), ethane, formaldehyde, methanol, formic acid, as well as gas temperature directly above radiatively heated wood samples. The combination of the fine spectral resolution and the broad bandwidth of the dual-comb spectrometer allows for precise separation of absorption signatures of individual molecules from the congested spectra. (c) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

This study demonstrates the application of mode-locked mid-infrared dual frequency comb spectroscopy for combustion analysis. By using the broadband spectrometer with fine spectral resolution and broad bandwidth, precise measurements of various gases during wood combustion process can be obtained.