Mid-infrared high-resolution dual-comb spectroscopy: Intensity, broadening, and beyond-Voigt parameters of ¹²C₂H₂ and ¹³C¹²CH₂ lines

Using a high-resolution mid-infrared dual-comb spectrometer operating in the 1300 cm⁻¹ spectral region, spectra of acetylene were recorded at room temperature. Spectroscopic parameters were measured in 3 vibrational bands of both ¹²C₂H₂ and ¹³C¹²CH₂. Absolute line intensities (S₀) and self-broadening coefficients (γ₀^self) were determined in the ν₄+ν₅, 2ν₄²+ν₅⁻¹⟵ν₄¹ and ν₄¹+2ν₅⁰⟵ν₅¹ bands. For the main isotopologue, the collisional narrowing coefficients (ν₀^VC) as well as the speed-dependence of the broadening (γ₂) and shifting (δ₂) coefficients were measured in the ν₄+ν₅ band of the main isotopologue of acetylene. Theoretical line-shape models were fitted on experimental profiles using a homemade multi-spectrum fitting procedure to determine spectroscopic parameters. Excellent agreement with the literature was found for self-broadening coefficients and absolute line intensities in the ν₄+ν₅ band of ¹²C₂H₂. For the hot bands, good agreement with the literature is found within experimental uncertainties, while γ₀^self of those hot bands are also reported for the first time. Similarly, the rotational dependence of ν₀^VC is found to be close to previous works. γ₂ and δ₂ of ¹²C₂H₂, as well as S₀ and γ₀^self of ¹³C¹²CH₂ are also reported for the first time in this band.